Of course, the first thing that most role-players think when finding rules for practicing medicine without the use of magic is, "why bother?" After all, magical spells are much faster and less problematic, yes? What party doesn't have a regeneration scroll just kicking around?
Well, my parties, for one. Regeneration is a 7th level spell and requires a 16th level cleric to cast. 16th level clerics are ridiculously rare and invariably very busy. Think of it this way: the pope can easily lay his hand on your shoulder and bless you . . . but given that there are a billion other people who want the same thing, the simple act of receiving a personal blessing is probably not going to happen for you.
In short, even if the party in an everyday munchkinish game has enough of every kind of healing spell available to ensure never having to worry about getting their hands dirty with ~ shudder ~ surgery, most of the other people filling all the towns and rural countryside of the world probably have little choice about it.
But why should that matter? Why concern ourselves with what the simple people do ~ we're busy adventuring here! We can't worry about what limbs or diseases the common folk care to die from ~ right?
This thinking expresses a kind of bubble that most campaigns simply ignore, one where the setting is built wholly upon the party's specific needs. If a member of the party catches a disease, no problem: we have a spell for that. If a member loses a limb, boom, here's another. If a member slips and falls among a patch of razor cactus, we have a handy rod of resurrection right here. The important thing is that we survive, we keep going, we get the adventure done. Other people don't matter.
Suppose the party, having just come from killing off an otyugh in some slime filled trough five miles into the forest, returns to the nearest village, all safe and sound. Quite by surprise, by the middle of the first night, half the inn's residents are mysteriously down with some sort of malady. The party is awoken by the tramping of twenty pairs of feet going up and down the stairs and with doors opening and shutting, because all of these poor souls have the trots.
The next day, finishing their breakfast, the party notices the bartender and the barmaid are clearly pale and in poor shape. As they collect their horses from the stables, they see signs of a spreading ailment everywhere: there are slop buckets full of vomit and rumours that half the village has been infected. As the party is saddling their horses, the chief magistrate approaches them, saying, "Within a single night, there are more than a hundred people who have some sort of disease! You must have brought it with you, you're the only outsiders here! What are you going to do about it?"
Well? What are they going to do? There isn't enough disease-curing and resurrection to go around for everyone, is there? And since the party are clearly carriers, as they are unaffected themselves, are they really going to go to another place and spread whatever they've got there, too? If they leave this horror behind, someone is going to have to deal with it. Sooner or later, someone is going to have to deal with the party, too, before their selfishness kills half the kingdom - just how hard do they think it will be to identify them and follow the trail of disease and death they leave behind them.
But this sort of thing never happens in most campaigns, because DMs don't think of it. Evil is something that happens to the party, not to the innocents . . . and the party is never at fault, never put in a position where their clumsy indifference to the world where they live eventually turns up some consequence they can't wave away with a single cleric.
I'm steadily coming to the conclusion that "simple rules" work for most campaigns because the adventures ~ and the problems ~ are kept as two-dimensional as possible. Simplistic adventures don't demand many rules. On the other hand, complicated situations and catastrophes can't help but challenge the magic parachute most parties depend upon, because usually they involve more than a population of just three to five persons.
Yes, I do know about the ridiculous healing rules that have been included in the Pathfinder system. They have been explained to me. Even those, however, falter when dealing with thousands of people suffering from large scale disasters and holocausts. No party, ever, has enough resources for everyone.
It's a question of how hard do we want to bring this home for them. It's hard to feel like a hero when we're lambing it out of town to avoid admitting that we'd rather just let people die rather than risk contracting the disease ourselves ~ even as we make excuses for our behaviour. Excuses, however, are a lot easier than performing ordinary, mundane, non-magical surgery for 42 hours at a stretch because we are able . . . long after the spells have run out.
Just for a little perspective: