I hate to imagine that 50 years later, Corporate Gary has won out over Hobbyist Gary in the end. But that's what it looks like. And through no real effort on WotC's part, either, even though it's obviously in their interest.
Much of the DIY culture in early D&D arose because--to put it bluntly--the rules were an insane mess. You had to hack them up and retool them if you wanted a good game. On top of that, TSR itself released all kinds of variations and customized rulesets, starting with the Basic/Advanced split, so even if you were determined to play by the book, you still had to decide which book to play by! The DIY culture was simply making a virtue of necessity.
Over the last three editions, however, Wizards has steadily improved D&D's ability to work out of the box. 3E standardized the ruleset; 4E got a handle on balance; 5E streamlined chargen. You no longer need a binder full of house rules to make the game work. And so now a whole lot of people are playing by-the-book 5E, and it is no longer taken for granted that every table is going to have its own customized game.
This isn't because Wizards has gotten more corporate. It's because they've done a better job! They made the game better and this is the result.
Now, it is an unfortunate truth about humans that many people like to condemn anyone who does things differently. Thus we hear a lot of cries that DIYers are perpetrating badwrongfun on their playgroups. Which sucks. But remember that just because you see it on social media, doesn't mean it's a majority view, or even a substantial minority. Social media amplifies the loud and obnoxious few over the quiet and reasonable many.