whenever this get's brought up, I always think of the concept of the "sift of time"
For every rock and hip-hop classic of the 90s, for instance, there were a couple of ultra-safe pop songs that we just don't remember because they didn't have a lasting impact. Fun fact: the top-grossing song of 1992 was some Brain Adams song know one remembers (tbh I forgot the name of it since learning about that)
If you want some modern artists that really push musical boundaries:
-1-800-PAIN is an experimental hip-hop duo that mixes gangster-rap with hyperpop, industrial metal and extreme noise music. They can be really challenging on a first listen since they experiment with intense levels of distortion, but their worth getting into
-WARGASM (UK) is a really great modern industrial band
-Rina Sawayama is an experimental pop artist from the UK that combines Y2k-era rnb with nu metal and rave, her song "XS" is simultaneously intense and catchy, and she mixes the oldschool rnb harmonies with burst of sludgy grunge guitars rather seamlessly
-Dorian Electra is another avant-popstar, but where as Sawayama's music is artful and restrained, Electra's music is completely bonkers. They have quite a few songs that veer into really unexpected directions (e.g.: "Ram It Down"). Dorian's music is influenced by everything from 80s pop ballads to extreme metal to happy hardcore, if you want something really out there listen to them,
or KILL KRYPTO!, but that's my own project so i'm being a little self-involved with that XD
btw i think the problem is less that good music is less common and more that the algorithms make good music harder to find