That's a long-winded way of saying that the lowest common denominator determines quality.
No. It's a very specific, sarcastic way of saying you don't have any idea what you're talking about. For someone who claims to know what's what on this score, you sure don't paraphrase well.
There is no "lowest common denominator" in this context. There is the artist, the artwork and the audience. That's it.
Vincent Van Gogh's work was deemed utter crap during most of his life. Now he's hailed as a visionary genius. Same painter. Same art. Different audiences. Different times. You lose.
If there is an ultimate, objective means of determining quality, outside of asking you what you think is good or bad, point it out.
You can't because it doesn't exist. It never has existed and it never will. Art is, by it's nature, a moveable feast. What's "good" or "bad" shifts from era to era and from region to region and from person to person. It is a protean activity dependent upon multiple, constantly shifting variables.
You can't cite an objective authority because there isn't one. Of course there isn't. The entire history or Art is against you. I mean 100%.
I don't think you like those odds.