The game of D&D, as I was introduced to it, provided a collection of rules that asked for the participants to succeed on their merits ... that is, the quality of being particularly good or worthy at the game's operation, so as to receive a reward following the game's play. Survive the dungeon, haul away the loot.
This expectation did not encourage a great number of participants, however, for numerous reasons. The game was not designed very well, so that "success" seemed to come more from pure luck than as a result of actual skill, or otherwise that success seemed to arise far too often due to the DM's inconsistency and obvious favoritism.
The presence of the DM was, in fact, a huge failing in the game. The ask for a single individual of dubious ability or personal approach to manage all or most of the game's play, without clear and plain guidelines provided by the rules, was a recipe for corruption, vindictiveness, ego and excessive advantage for the DM's favorites rather than equal treatment for every player. Although the potential the DM's presence offered for a game, increasing it's scope and excellence beyond what most games could provide for participants, that promise demanded far more explanation and demarcation of the DM's role than the game's original writers were either willing or ABLE to produce. So, instead, despite efforts to explain what the DM was more than what the DM absolutely ought not to do, the actual can of making the DM's place in the game legitimately was kicked down the road ... where it has remained, unsolved, to this day.
Instead, energy has instead been given to commercialise the DM's role by supposing that providing modules would, magically, cause the DM to cease being corrupt and would instead run the game like a robot. At the same time, excessive effort has been made towards specialising the game's character, almost to the exclusion of any other writing about the game, by providing more classes, more races, more spells, more magic items and more monsters for the character to fight ... while utterly ignoring the player's actual participation, such as content clearly indicating the player's responsibilities towards other players, towards the DM, or even what the player's place in the game is. SOME of these things have been casually and inconsistently been written about on the net for the last twenty years, but since the "official" company refuses to weigh in, since taking a stand on anything might threaten profits, no agreement has ever been achieved by any group anywhere.
The closest that anyone has come to policing player behaviour has materialised as a set of approved condemned subjects that players are NOT allowed to present in play, for the sake of creating a "safe" space, which turns out to have nothing to do with game play and everything to do with morally provocative people seeking to censor the game's communication for political reasons. To the best of my knowledge, this putsch has failed, since I rarely hear anything about it in mainstream circles, but then I spend no time at all reviewing pages on Reddit, Quora or other popular but academically deficient circles.
Therefore ... without formal communication to the contrary, the success that was intended to evolve from the player's merits has been shifted to choices the player makes which ensures the character's success, regardless of the game's play. Essentially, as soon as the character is made, the character is already a success, and everything afterwards is mere theatre, like a Kabuki theatre, where all the stories are already known, where the actors movements are already known, and in which the end is already known. Participation is, therefore, reduced to ritual and expressly for the purpose of obtaining satisfaction from the ritual being performed correctly. That is, to produce "fun" that is less spontaneous than a mere repetition of player-used phrases, like having the players constantly checking their perception.
It's no wonder that after two or three years of this, players drop out to seek other forms of amusement.
What the game has become also explains the survival and appeal of the "old" game, which the modern version has failed to stamp out. Since the old game isn't officially popular, DM's who play the old game cannot rely upon an easy acquisition of players ... not that they ever could. This acts as a heavy deterrent against DMs who are corrupt, since expressing a willingness to play the old game is already a difficult hurdle for new players — who are less encouraged to tolerate a corrupt DM when the system is unfamiliar — or for old players, who know better. Where the DM is compassionate, fair and legitimate in his or her presentation, however, old D&D continues to offer a gaming experience that new D&D simply cannot produce. For a grognard like me, this makes hunting for new players like fishing in a barrel. I never lack for experienced players, bored as shit with new D&D, who are anxious to try a more meatier game ... and since I can deliver, I never need worry that my game won't measure up to the Kabuki theatre the company provides.
This is why I believe that old D&D won't disappear when the grognard's generation passes away — because the earlier game IS superior, vastly so, though it requires a practical-minded DM to adjust and shape the old game to make it palatable in a way that the original founders were incapable of describing (or even recognising that it needed to be described). My generation is already producing a field of 20 and 30 something DMs who are seeing the game for it's original value, who will be hardened grognards themselves in another decade or two. There will always be cast-off players from the "official" bullshit system able to recognise what new D&D might be, despite what the garbage face it shows. Those players will never have to build a proper D&D from scratch ... they will always become aware of what's out here, despite the company, because we always will be out here.
We love this game. And we know how to make others love it.