I got into the hobby in the 90s — the 1106 D&D tan box and AD&D 2nd Edition — and the way everyone around me played was trad. Plotlines, protagonists, and playacting. If you could railroad under the table to make a story happen, awesome, that meant that you were a good DM who cared about narrative and theme and characterization. Player agency? Not a concern. Everything had to serve the story. And players weren't there to be challenged, they were there to get into character and portray their characters, ideally with full-on voices and thespianism, end of story. Or at least, until the end of the story.
It took me several years to notice that this way of playing D&D (a) wasn't particularly fun for a lot of players, and (b) was incredibly
stressful to DM, especially if you felt like you had to keep yourself one session ahead of a few different possible branching paths the players might take. Add to that, by the time 3.0 was transitioning to 3.5, character builds and heavy rules systems were making D&D just plain burdensome to deal with at the table.
So I went back to the tan box and from there the Rules Cyclopedia, and the lighter systems eased the burden a bit. But it was really the OSR philosophy (think Abed Nadir: "I'm the Dungeon Master. I have to be impartial, or the game has no meaning") that makes the game runnable. Build a world, make it a lively and dynamic sandbox full of interesting discoverables and interactables, and then stop caring what happens to it. Turn the PCs loose on the sandbox, and then just let the game run itself. Play to find out what happens, and instead of being the maestro Houdini who pulls all the puppet-strings and effects all the outcomes, just enjoy that you get to be surprised.