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.