My son (@cmp2020) and I have variants of this conversation all the time. To what extent does the authority of the artist define the quality of the work and to what extent is it determined by the market?
I tend to place more reliance on the market, but that's only true over long time scales. He constantly brings up the examples of Franz Schubert and Emily Dickinson, neither of whom had commercial popularity until after their deaths, but obviously they knew that they had written quality works. And, of course, we have no idea how many high quality works have been lost to history.
I don't think there's really a black & white answer. If we're talking about technical correctness, obviously the trained musician knows more than the casual listener, but (IMO) that's only a partial evaluation.
I agree with your point of view. Some of my friends, being musicians, may have a different opinion, generally not connecting 'quality' with market. But I suppose, they think like that because they are musicians and although they indeed produce music with a certain complexity, something different then the standard (both aspects I like in music) making it a certain quality in my book, they want to differentiate from all those musicians producing relatively simple tunes, easy to listen to, easy in everything, which in the end is more the music for the mass, or at least, the mass generally likes to lesser complex music. Since, I'm not a musician, I can look at things in a different way, I suppose, kinda like how you think. The market determines in the end what 'quality' is and I'm pretty sure a lot of 'quality' music got lost because the market didn't find it quality enough :)
I'm not sure I agree that over the long term that low quality works get lost. Often, the long term survival is also a tendency of taste. In Early Music, our work also focuses alot on the rediscovery of "lost" works and composers. You'd be surprised how many gems there are! Of course, there are also troves of derivative works....