These two attitudes would be as follows: those who become so wrapped up in the reality that is being depicted that they seem to forget that this is a game, and those who become so wrapped up in gamesmanship that they seem to forget that it is meant to be an emotional experience.
Without defending that is that sort of experience, and without needing to defend that it is a game, let's consider instead why or how these attitudes arise, without the usual Alexis-style inclination to superiority.
Gamesmanship seems to be a watchword of late. Wikipedia calls it ". . . the use of dubious (although not technically illegal) methods to win or gain a serious advantage in a game or sport." Please do have a look at the whole entry, and give thought to the fact that this is a circumstance that arises in every other game that humans play. With that in mind, it's important to realize that the 'need to win' is a human condition, that arises from more than just want RPGs call rules lawyering or power play.
Where would that need to win come from? First principles dictate that we examine the people who practice gamesmanship for an answer. An obvious theory is that the individual believes that they're unable to 'win' without practicing gamesmanship, but I find that's a simplification. As humans we are biologically programmed to seek not only success, but success at the least possible cost. This means, you might be able to kill the mastodon with a spear, but it is a lot easier to make the mastodon walk off a cliff. The fact that you do the latter does not prove that you cannot do the former, or even that you wouldn't do the former, if you were compelled to. It does mean that you'd rather be somewhat farther away when the mastodon dies, as the meat tastes the same and your life was never in danger.
Thus, the player might be able to play on an equal level to anyone - it's only that they've found it easier to WIN by 'breaking the flow' of the opponent, messing with their head, etc. Technically, the 'gamer' (if we can co-opt the term for the basis of this post only, as someone who participates in gamesmanship) has merely evolved a better set of practices in order to win the game. If winning games defined the survival of the species, gamer clans would out compete non-gamer clans. Which is actually what prehistorically occurred.
But, this is not survival, this is real life. So we must assume that somewhere down the line, the gamer skipped over the social compact of playing the game in a polite, pleasant manner (quite a lot of gamers, I'm sure, have been punched out and dumped in the alleys behind pubs because they won't shut up while their opponents throw darts). Why does the gamer not view the social compact as more important than winning?
Because the gamer does not feel the compact. Of late I've been parsing out the brilliant content of this video, which goes into the differences between endorphins, dopamine, seratonin and oxytocin. While the reader should get a look at the video (yes, more homework!), I'll cover this quickly. Oxytocin is the good feeling you get from being with friends, from hanging with them, from the sense that you're safe and that they are your people. You feel good. That oxytocin.
Seratonin is a drug that your body produces that makes you feel good when you've achieved control, or status, or that you've done something to be proud about. It's the feeling you get as a DM when the players tell you that you're amazing, or when they're all listening closely to your every word. Feels good, doesn't it? That's seratonin.
When you are at a table playing the game for the sake of the game, and having a really good time because you're with your friends, and the game is great and the chatter is good, and you feel like this is what the game should be, you're looking for that oxytocin high. But when you're with one player who's trying to play the system and make it work their way, to get the items they want and the things they need, to feel strong and powerful, they're not looking for oxytocin. They're looking for a seratonin high. And that's why it feels wrong. You, me, all of us - we're just bags of chemicals. And when the chemical you're wanting isn't the same chemical they want, things go bad.
Now, it's no one's fault. Some people get a better high from seratonin than they do from oxytocin, because they're built that way. And the reverse is true, too. When you're telling the seratonin-user to relax and not make such a big deal of the game, you're essentially saying, "Hey, stop using your drug; use mine." But the seratonin-user has probably tried your drug, and the high they get from oxytocin isn't as HIGH as the one they get from seratonin, so from their perspective you're really saying, "You're not allowed to have as much fun as you can."
And when you, the seratonin-user tells the others, "Hey, you gotta play harder, you gotta go for it," they don't agree, because they're getting a way better hit from oxytocin than they've ever gotten from seratonin. So they don't get you.
And that's how it goes with humans.
So let's look at the other thing, those players - mostly DMs - who are more interested in the reality of the game than they seem to forget that its a game. What are they getting high on?
Dopamine is a drug your body provides you with when you found what you're looking for, or if you've accomplished something you've set out to accomplish. Video games are huge dopamine providers. Everything in a video game is designed to trick your body into thinking that it has done something that will contribute to your survival - and whenever you do anything that will contribute to your survival, your brain activates the hormone that produces dopamine, and you get HIGH.
The reason why the coins make a little sound when you grab them in Mario? Dopamine. Your eyes, linked with your hearing, reacting to a sound that is similar to the sound of a stone chipping off a bit of flint on an Acheulean hand axe, which our ancestors chopped and made for perhaps a million years or more.
You grab that little coin, you hear that little *ding* and . . . dopamine.
We get our dopamine hits in all kinds of ways. I make maps, for instance. And fundamentally, there is an equation between making something realistic in the game and getting a really solid dopamine hit. The more 'real' it is, or the more 'real' it seems, the bigger the hit, so we feel something really profound when we realize that weapons hitting shields should splinter them, and we make rules for that. We think weapons should hit different parts of the body, so we make rules for that. We think healing plants don't all grow at the same rate, so we make rules that say these plants will heal as much as this, and those plants will heal more. Then we ask the players to lay out multiple pages of notes and accounting in order to compensate for all the rules we've just made. At some point we've forgotten that we're making a game in favour of making our own personal Acheulean hand axe. Because we get a WAY bigger high from dopamine than we do from oxytocin.
This is a sort of DM thing. Oxytocin is nice, but the dopamine high mixed with seratonin is better. Except that when we have a player that's got a seratonin fix, the DM's leadership is challenged, undermining the DM high, and conflict erupts.
Yes, like I said. You're a big bag of chemicals.
Some of you might be asking, what's the answer. Well, there is none. A seratonin-user isn't going to get as much from oxytocin as someone else might, and that's biology. That's out of our hands. All these chemicals arise out of the body's autonomic response system, the hormones, which is a form of evolution that predates the spinal cortex, but which we've inherited because we ultimately descended from worms. We are stuck with these chemicals. We can't think our way out of them.
We might, conceivably, take a stand that we're willing to relax our personal need to get as high as we are able for the sake of the general interest - but that is going to mean establishing a general interest that embraces everyone at your gaming table, as well as yourself. For example, that this is a game. That it is meant to be played as a game, by rules we all agree on. We need to agree that our individual dopamine, seratonin or oxytocin highs might need to be acknowledged and managed.
But let's admit something. Oxytocin is the good drug. It's the community drug. It's the drug that doesn't depend on serving yourself (like dopamine) or pronouncing your dominance over others (like seratonin). Oxytocin is the drug that makes us feel glad just to be together.
We need to get high on that.
