Well, I sort of believe that the cream rises to the top.
How do you define "the top?" Album sales? Concert attendance? Critical acclaim? Longevity?
It doesn't matter; "Back In Black" sold a bazillion albums for a reason. Taylor Swift sells out stadia on a regular basis for a reason. The Velvet Underground are widely acclaimed for a reason. The Rolling Stones have been an active unit for 55 years for a reason.
"Good" is purely subjective, a matter of taste, but when you get to the objective standards you're talking about above, I believe that generally, overall, there is a reason for achieving those standards.
I think there's a reason too, but that reason doesn't mean those songs are "better" or worthy of winning one of these roulettes. Rush has said quite a few times that if they'd started today, they wouldn't have achieved anywhere near the level of success that they did. But does that mean that, even though their music wouldn't have achieved the same level of commercial success, that it wouldn't be as good as you and I both think it is? Of course not. There are tons of factors that go into what makes something commercially successful.
I'm pretty sure Rush's comment was in the context of the music business. They wouldn't have been allowed to get to album four before they broke through. That's a different problem, though, and indicative of the number of artists vying for listening space.
But take a step back. I'm not JUST talking about commercial success. I'm saying that whatever reason YOU have for getting into that Belgian-Norwegian Dark Grey Near-Death Metal is no better, worse, smarter, knowledgeable, or special than the 19 year old who gets into Taylor Swift. That's all. You just have to acknowledge the standard you're using. I suppose there is music that is never meant to be heard, by anyone (didn't Zappa do something like that?) but that seems counterintuitive, so if you assume that all music is meant to be heard, then it's all about the reaction to that hearing, whatever that reaction is. Musicians in a niche genre making niche music that end up niche artists, well, they reap what they sow.
As for Van Halen, pick a standard, any standard. Except for "operatic vocal excellence", they qualify as one of the greats. Albums sold (two diamond records); as a touring act (they can do at least arenas without an album, no problem); influence (look at LA circa 1984 and count the VH/DLR clones); musical achievement (EVH is widely and rightly considered one of the greats in the field of guitar); music bsiness (they innovated several things that are now common-place in the music industry)...
I'm not a music expert, but I've been listening for the better part of 40 years. I've recorded and played my own music (and others). I know enough about music theory to be dangerous. And for me, I refuse to dismiss Taylor Swift as some sort of gimmick or fad or dumb luck shot, just because her lyrics don't really resonate with me, or there is 1/4th the number of notes per measure as the last Sons of Apollo record. If it was so easy to do, everyone WOULD be doing it (because there is a shit ton of money to be made, if nothing else).