Originally Posted by Frownland

I think that the Nirvana/the 90s/Lil Wayne/the boogeyman killed music mantra is likely pushed by the music industry in response to organic artistic shifts so that they can provoke a reactionary sell-off of the remaining supply of albums they feel will fall out of favour. Now that new artists can put out their new music digitally, industry giants are focusing more on reprints because they have a built in nostalgia market, plus they can market it to the younger crowd that they sold the Music Is Dead myth to as Good Music They Don't Make Anymore. Once time sifts the sands of digital music and some level of cultural consensus is reached, those albums get added to the nostalgia cycle.

Any parameters used to establish an objective standard of quality will be based on subjective preferences. Restricting the conversation to top-selling radio charters when radio and physical media are declining in prominence will deterministically lead you to the conclusion that music as a whole is on the decline. Unless you're talking about song length, number of instruments, and so on, there really is no objectivity in music.