[bluetomcat]

Probably disco was still important, but the mentioned artists were hugely popular and influential, despite not being strictly in the "pop" category.

[N1H1L]

Also disco, when it first appeared on the scene was strongly associated with an LGBT audience, and the Moral Majority crusaders then absolutely denigrated it.

Good art is by definition subversive, and you won't find subversion in the Billboard Top 40. Which is why conservative criticisms of stagnation in art/science feel so blatantly hypocritical too.