My theory is the 60s/70s were a bit of Cambrian explosion from the perspective of music.
Music wasn't shit before that, but there were rules. Fair enough, black people might have gotten up to wacky stuff with their Jazzz and so on, but in real terms there were rules and you operated within a framework.
Then something happened (heh) in the 60s and bands realised that they could do some wacky shit themselves, and still flog records. I don't want to bring up The Beatles, but... The Beatles, you can see them doing shit songs, that followed the rules, until at some point the penny dropped and they started doing anything they felt like more or less. The record companies, who'd normally tell bands to go fuck themselves, were in a tricky position because they were clearly raking in cash.
So now bands, who'd been hired under one set of rules, realised that they too could do wacky shit, anything at all was fair game because the record labels had been wrong footed and didn't know what the rules were any more. Some cunt who lived in the bedroom of his parent's gaff assembled a weird guitar riff and then fucked a load of bonging bell yokes onto it, and seemingly this worked? Tubular Bells is a thing now is it? Huh. OK.
So... like, what else is a thing?
So you had this really constrained, careful, conservative industry, which realised almost overnight that they really didn't know what was selling records any more. Bands had always been doing stuff, but the industry ignored it, then a transition occurred and suddenly the industry said fuck it, try stuff, put it on TV, see what sticks.
