suddenly it was possible [to have] a pop song without harmony
If that was in 1991, then I guess Napoleon XIV must have been some sort of visionary? That came out in 1966 and although the wiki link doesn't mention it, I recall reading that he was denied composition rights (iirc) because it didn't have any of the usual elements of a "song", most notably not having any "notes" (no pun intended, it's all just glissando with no fixed stops). I think that the link here might explain that in point 5... he lost certification from the American Society of Composers, Authors and Publishers.
Also, while I'm talking about pre-dating, how about Blondie (Rapture, 1980) and Gil Scott-Heron (TRWNBT, 1970) as rappers/proto-rappers? And obviously there were tons of electronic artists before the 1983 cutoff (like Bruce Haack, but many before him, too). Less eclectically, Telstar was a massive hit in 1962...
Biting the hand that feeds IT
