Buddy, repeating an opinion then stating that it's a fact does not actually make it a fact. You, nor any other human being on this entire fucking planet, cannot objectively say that BfA and SL are "inferior versions of Legion" because you do not get to speak on behalf of every WoW player in existence.
In a game with as broad of a playerbase as WoW's, you're never going to get a consensus on things that are loved or hated. For every corollary you find, there are plenty of people on either side of the issue. For all the pro-fliers, they're just as many anti-fliers. For all the people who loved AP, there are just as many who disliked it. You are making an incredibly lopsided argument that simply because Blizzard changed something later on down the line, that must mean that their initial roll out of the feature was flawed and the only reason they ever did it any other way is because, well, fuck you I guess? This is simply the wrong way to look at the way Blizzard processes feedback since you're always going to fall victim to
negativity bias. The other important thing to consider is that despite all of these flaws, WoW considers to be immeasurably profitable for Blizzard which means either people are paying for a product they hate (unlikely) or these game breaking issues you hate and equate to being "inferior products" aren't nearly as universally derided as you'd like to think.
In addition to the video I just linked, I'd also recommend you read
this article by Ghostcrawler because he does a better job explaining these concepts then I ever could. But we both know you won't because you're not interested in learning about game design theory; you just want to win an internet argument.