Here let me give you a different example, both me and Gaidax who's conversation you hopped into predominately played destruction, even when it wasn't the best spec.
There's always the 3 aspects, gameplay, aesthetics, and power. They all have an affect on anyone's decision to varying degrees depending on the situation.
For instance for me personally:
If we're talking about races, that'd be an aesthetic and power choice with not much if any gameplay involved. The power difference is fairly small (usually 1% at the extreme ends) so Aesthetics win out there.
For classes, I love the warlock theme and warlocks have always been top tier, they've got aesthetics and power down for me. Unfortunately I absolutely hate what they've done to the class from legion onwards, so they fail gameplay for me and I'll be changing to a new class. Gameplay beats out aesthetics and power here.
So when it comes to covenants, there's so many layers here because they've up and decided to house so many different aspects under one single choice (which is the contention). Ultimately gameplay is far and away more important to me than anything else, so that will be my immediate concern when picking anything and the covenant choices could actually affect what class I'll end up playing just to avoid certain buttons since I have multiple classes I could see myself otherwise playing. I'd rather be able to pick the strongest power related choice that I also enjoy playing on a class (spec) I enjoy playing than have to compromise somewhere. I don't feel strongly enough about any of the aesthetic options presented as I think all the themes look good as far as I've seen and lore is pretty much irrelevant to me, so those are both less significant to my decision there. Pretty much the only one out of my potential choices that I outright want to avoid like the plague is the warrior banner. If I were to choose to play warrior and they did a tuning pass that made the banner better I'd still likely not take it because I don't like it mechanically and vehemently dislike it aesthetically.
I type all this^ to give you a kind of idea of whats running through my head when I make those decisions, me being someone who was raiding in a US top 10 guild (peaked world 24th) and is the exact kind of person that people on forums like these will try and speak for and say we only care about power and will do all sorts of outrageous things for .5% power increases etc etc that we absolutely don't do. These people really have no idea what they're talking about, but they sure love to tell me and others what people like myself think.
High end players dislike how this system is designed specifically because they care about more than power, but if blizzard forces us to choose between gameplay, power, and aesthetics, we're gonna do what we have to to find the option with the least compromises for us.
2002 blizzard knew this though:
https://i.redd.it/ukdusghmghm51.png
It can't be both "a vocal minority" and something completely prevalent and pervasive across the entire pug scene and most of the community.
Its very much the average player perpetuating this, otherwise it would be insignificant and we could just ignore it and pugs wouldn't take hours to get into if you aren't the right class min-maxed with better gear than you need for the content you're pugging into. Its absolutely the average player.
That's pretty much the rub though, blizzard is implementing these systems that are hampering peoples fun. Hence the push back.
One of the biggest things I loved about playing a pure and a big part of the reason why I played one was that I got 3 separate unique specs that gave me dramatically different experiences with very different kits and a myriad of options. Pre-legion I almost always played all 3 specs in every raid and had that varied experience.
From legion onwards they keep putting in systems that pigeon hole me into a single spec, which takes away from my fun as I no longer get the varied experience I used to. Now they're adding in yet another system where I'm meant to stick with 1 thing perpetually so that it can get stale instead of letting me have a diverse experience.