The progress in music has been continuous since the cave man, although at a greater pace. Each generation identifies with stuff they grew up on. Each generation has some really great music to add.
I grew up, basically on The Beatles —-> rock of the early 70’s. I loved music. I became a Geologist… worked by myself and music was my companion. I found fussion jazz… then traditional jazz, then classical, then before I started traveling the globe extensively world, then electronic. I would dive into each and be overwhelmed with some of the best of their tine. After some thirty years or so, I rediscovered Rock. I found there were many great bands. I was later surprised to find some amazing and exceptional Hip-Hop and world fusion.
I now listen to streaming…. Which sounds as good as vinyl on my system. I find incredible new music from here and there all over the world. A great example is the Afro-Celt Sound System. While not recent… this kind of fusion goes on everywhere and with increasing frequency.
The increase in availability of great new music is unreal.
I think any indicators pointing to less great new music are flawed by looking at too narrow a selection of channels.