I would agree quite strongly here. I make a point of grubbing through "new artists" and/or "new releases" on Amazon Music or Google Play Music.
"New Sounds" are simply extremely rare, or alternatively, inaccessible (by inaccessible I mean something like "I've Got No Chicken But I've Got Five Wooden Chairs" by Barton).
Of course, this is separate from my tastes - I'm searching for something that is an enjoyable new thing that tastes good and unlike my existing taste.
My personal guesstimate is that the wide availability of sounds has provided a too large landscape for newcomers to work through and then break out of, in general. It will almost take a naive art type to synthesize together a new sound that is both accessible and fresh - in my opinion.
Moses Sumney, for example, is incredible. Give this a whirl. https://www.youtube.com/watch?v=NPeji3NS4uE
Mr. Sumney is, I'm sorry to say, not dramatically variant in the indie folk sonic system. I would say that it is a somewhat more electric orchestration of someone like Jesca Hoop; the sonic textures are similar. I don't care for falsetto - tastewise - I've run into a few other groups that are similar sonically over the past half decade besides Ms. Hoop.
It's plausible Mr. Sumney will evolve for a time and be substantially different - Doomed from that video presents the possibility unambiguously - but musically I would locate him in the indie-folk sound, with a different instrumentation and more electric usage.
Wasn't that maybe because of the incredible evolution of music hardware? 70s music was IMPOSSIBLE to produce in the 60s, 80s music in the 70s, so on.
Today that hardware evolution is slowing down, so it's normal that the sounds don't change that much.
But neural networks are on the horizon, expect shocking things in a few years.
It's not just the hardware.
Stravinsky's Rite of Spring could have been composed hundreds of years ago on basically the same instruments, but it wasn't. Nothing remotely like it was.
Twelve tone music, Dada music, all sort of other types of music could have been composed hundreds of years earlier, but it wasn't.
It's not just hardware and technical capabilities that evolve, but musical tastes, ambitions, and understandings of what music is and could be.
Similar things happen in other arts. The Black Square[1] painting could have been painted at any time. But tens of thousands of years passed before anyone did it.
Art is constantly evolving, and the boundaries of what is considered art and what people appreciate as art is ever growing.
> Stravinsky's Rite of Spring could have been composed hundreds of years ago on basically the same instruments, but it wasn't. Nothing remotely like it was.
You are grossly underestimating the effect that technology had on music. Rite of Spring couldn't have been performed until the 20th century so there was no point in writing it.
Bach's children and Mozart (mid 1700's) were the first products of music pedagogy. Paper didn't become common until the 1800's. Interchangeable parts and factory practices made musical instruments much more consistent and available in the late 1800's.
All of this means that the average orchestral musician improved dramatically in capability over the course of less than 200 years.
> Some rap seems to still be innovating, but rock, pop, and a lot of electronic music seems to be stuck in a rut.
Now that everything is available on-demand via streaming services, new music is competing not just with a glut of contemporary works, but with the ever-increasing body of prior works.
Why try something new when you can listen to your old favorites at any time? Unless the new thing sounds a lot like the thing you already really like.
If you compare music from 1960, 1980, 2000, and now (almost 2020) you'll notice that the 60's to 80's to 00's were incredibly different. Like, they clearly come from distinct eras.
While there is still innovation, there aren't dramatic changes happening as often in the past two decades. There are many popular songs today that could have been popular in 00's and vice versa.
Some rap seems to still be innovating, but rock, pop, and a lot of electronic music seems to be stuck in a rut.