Plus, The Winnowing: We don't listen to most music from decades ago. We don't listen to most hits from decades ago. The Winnowing removes most works, in every medium, from the popular consciousness, leaving only the consensus favorites, also known as the canon.
Here's an example: "The Ballad Of The Green Berets" by SSG Barry Sadler was number one for five weeks in 1966, tied with "California Dreamin'" by The Mamas And The Papas. That song is effectively gone now. It's no longer remembered. It didn't make the canon, because The Winnowing got to it, so now it isn't part of The Sixties as a consensus mass memory. "California Dreamin'" which was objectively just as popular by the metric of the charts, however, is pretty well remembered and is, therefore, part of the canon.
I agree with you in part, but feel there's something to the criticism as well. You can look at the top hits --- number ones, top 10s, Billboard top 40, etc., going back through time. And whilst the most popular song of any given year or decade often is reasonably banal, it often isn't, and as you go back through the list, there are dark-horse pieces which do appear.
Another factor is that far more music is published or streamed now, which makes sorting through the mix much more challenging.
Popular taste and memory are both fickle, and one thing that makes going through back-catalogues and earlier periods so interesting is that the sounds of forgotten hits are often fresh to modern ears, while at the same time being tinged with nostalgia based on style, composition, performance characteristics, etc.
If you look at popular hits going back about 150--200 years (say to the 1820s -- 1870s onward), one characteristic that becomes overwhelmingly apparent is the role of technology in popular music. Earlier pieces are often meant to be played or sung by the masses themselves, and tend to instrumentation that would have been available (fiddle, flute, piano). The first recorded formats were player-piano pieces distributed on rolls (and with a distinctly mechanical sound). By the early 20th century, amplification starts to emerge, allowing smaller acts, then electrification (the 3--4 piece rock group emerges), synthesizers (1- and 2-person acts), rap DJs, and over the past decade or so the ability for either a single person to play multiple tracks or for artists in remote locations to be able to collaborate on a single piece.
This may give rise to either original pieces, or simply amazing covers of classics. Leonid & Friends cover of Chicago's "25 or 6 to 4", for example, seems to me better than and at the same time more faithful to the original. It is technically fantastic, while at the same time having its own honest spirit and vivaciousness:
I still think that songs such as "Gangnam Style" and "Someone That I Used to Know" are both truly good recent (post-2000, for me) songs. Both in originals and covers such as Walk Off the Earth's: <https://piped.kavin.rocks/watch?v=p4hIzgqA9io>. (Not to mention the parodies of the original and cover versions...).
That said ...
... I listen to very little contemporary music, largely preferring classical and jazz / blues / folk traditions. Terrestrial broadcast radio is all but completely dead to me. And I don't use streaming services, so that's not really there either.
Here's an example: "The Ballad Of The Green Berets" by SSG Barry Sadler was number one for five weeks in 1966, tied with "California Dreamin'" by The Mamas And The Papas. That song is effectively gone now. It's no longer remembered. It didn't make the canon, because The Winnowing got to it, so now it isn't part of The Sixties as a consensus mass memory. "California Dreamin'" which was objectively just as popular by the metric of the charts, however, is pretty well remembered and is, therefore, part of the canon.
https://en.wikipedia.org/wiki/The_Ballad_of_the_Green_Berets
https://www.youtube.com/watch?v=8kj9qv6rmG8
Newer music hasn't gone through The Winnowing. More of the chaff is still remembered. Therefore, it all looks worse.