So I think you're right in a lot of ways. But I think your understating a few things.

First, OGL. OGL was great for 3.x edition. It spawned a cottage industry of 3rd party content creators, which by the end of the life cycle, had created content that which was smoother and more refined in the engine than anything WotC ever produced. This allowed 3.x to dig in and become immensely established. The problem is is that it cuts both ways; in 4e era, WotC's biggest competitor was actually Paizo.

I liked 4e, I think its better than 5e. But WotC became way harsher on piracy and 3rd party content in that era. The way powers were structured and templates, it became impossible to keep up with everything without their builder spoon feeding it to you. They were really pushing their "adventure tools." These were buggy, half of them never came to fruition, and they didn't run on mac (even though they were browser based). They only stopped pushing them after they bought a third party site (D&D beyond, which I actually ban from my games). I'm just saying that 3.5 was an accessibility dream, and 4e was actually behind lock and key.

Meanwhile Paizo had the immensely easier job of selling 3.5 weirdos back 3.5, and WotC couldn't stop them because of the OGL. For a while, I thought Paizo was actually doing worse damage to the industry; I was afraid no one would want to innovate if people were just going to play 3.x until the end of time. I guess I was right, because 5e is basically 3.5 will all the interesting parts cut off. And thats why WotC was trying to kill the OGL last year, in the weird way they did. They want the control, but they want the 3rd party support too.

The other thing you understated was just how many grognards there were for 3.x. I literally had a 5e baby pitch to me a cyberpunk 2077 game that he would run in starfinder, but 3.x guys refused to try out 4e. Their complaints were as many as they were meaningless. Orcs aren't core? All classes get spells? I can see the WoW recharge timers! A lot of enfranchised gamers simply did not want to play a new game, and then PF came along, and they did not have to. I saw it happen in my game group, but this also was borne out in paizo's ascendancy in this era.

I want to say one thing to your point @Colalextrast@lemmynsfw.com, that 4e had too much bloat; 3.x had a ton of bloat as well. At least every power in 4e was like, functional. 3.x had dozens of base classes and hundreds of prestige classes that were traps. Hundreds of feats that were not good. I think 1200 officially published spells (at least you could swap those out). The only reason 3.x combat wasn't a crawl was because it was rocket tag; high level spellcasters usually end the fight in one move.