I've been D&Ding since around 1980.
I started with the Moldvay Basic Set. It was all new to me. The entire thing was a big invitation to create a world of my own and find others to explore it. Ditto, the Expert Set.
I've never run anything but my own setting.
Through the intervening years, there have been a great many settings, editions, supplements, and support material for the game. For the most part, I've kept pace - if not in actual gameplay. And, while I don't deride others for their preferences in D&Ding, I find that some are perfectly willing to belittle mine.
Since when is B/X D&D "a kid's game?" Or, "an introductory set of rules to learn the real game?" If I were going to get nasty about it, I would point out how much the current editions of the game (including Pathfinder) hold the player's hand and ease you out of the gate as a full-fledged hero ready to take on carefully balanced encounters set neatly in your path in proper order and time.
Sorry for the pause, I had a great big yawn sneak up on me.
I've played 3E. And 3.5. I've read 4E. I've played 5E. I've played Pathfinder - hell, I've written Pathfinder material for publication. I simply prefer AD&D, and those which came before. I'll play just about anything. I don't force my preferences on anyone - even though I am now considered an OSR publisher. Outdated Simplified Rules - amirite?! Yep. So Outdated. So Simplified. Not nearly enough Rules.
Yeah, I happen to enjoy the process of forging a hero through fire and unknown dangers. Not everyone does. Not everyone can handle being a Feat-less nobody with a hand-me-down sword and boundless curiosity. Not everyone can face challenges without having the solutions written on a character sheet in front of them. Not everyone wants to. Not everyone needs to.
With each edition came new approaches to gaming. Innovations. Shifts in "power" or "control." Keeping PCs alive. Allowing players to craft their PC the way they want. Never saying no. Never slowing or stopping the action. Not wasting time with "background stuff." Never failing.
During the rare instances where I game as a player, I tend to be tactical AF. I prefer to run what I call "problem-solvers" or "troubleshooters." This usually entails a thief-type or arcane spellcaster - preferably a mix of the two. That's just how I think. And I will scrape every bit of potential from those characters. Feats might not exist in "old-school" D&D, but they really do. If I want to take a point-blank shot in combat, I'll get into position and take the shot. The DM decides what happens.
And that's really the thing. Trust in the DM. With trust in the DM, you don't NEED all those pages of character sheet, cluttered with modifiers, feats, and special superpowers. As a DM, I am willing to do just about all of the work. As a player, you just need to be able to run your character. In an ideal world, the player should barely need to look at their character sheet. There should be few moments where the players need to pull themselves out of the game to look up a rule or modifier. At least, in MY ideal world.
My ideal world turned out to be Avremier - my lifelong campaign setting. At its heart, Avremier is an exercise in making the rules and structure of the game work in such a way that I can be happy. Why are humans the only ones allowed to advance in certain classes - or to such high levels? Why can't demihumans do the same? Why can't magic-users use swords? Gandalf did! What's the point of gnomes? They're just halfling-dwarves! And so on. Yes - those questions are addressed in Avremier. And, many of the rest.
Lots of people love D20 and Pathfinder and 5E. I get it. I did too. Today, I prefer the older stuff. I don't have to spend money and shelf-space to maintain the game. I can convert "new stuff" to "old stuff" in minutes. There's less math - I don't like math. I can focus more on the adventure. On the game. No, the later editions are not WRONG. They're just not right for me.