A few things were going on. First, hetero America was still coming off the "free love" era of the 60s/70s. Time magazine famously ran a cover story announcing the end of that era-- and that was somewhere around 1984? Most Westerners, straight and gay, had a mindset that STDs weren't a big deal. Pop some penicillin, nbd. /*
Gays in America, as a community, were only beginning to publicly assert their rights beginning with the Stonewall riots in 1969. As with any civil rights movement, it takes years to build momentum, and there's lots of opposition. So gays came into the 80s with a combination of freedom and fight; it was the most open they'd ever been and that was celebratory, but conservative voices were also increasingly speaking out against them because they were more public. For a lot of gays it was an exhilarating time where every act (including sex) was also activism. Warnings about STDs, and particularly one first called GRID-- Gay-Related Immunodeficiency Disease-- were often viewed as scaremongering tactics by conservatives. Can you blame them? A non-sentient disease that happens to only target gay men, just as gay men are taking their place in public society? Uh huh; tell me another one. /**
So yes, people knew about vd (STDs). But for decades they'd lost their frightening aspect because of penicillin which, wonder drug though it is, people frankly overestimated. (Antibiotics will kill many, but not all STDs.) The gay community got a late start on public free love (and frankly, they couldn't be all that public about it either) and, more importantly, gay activism was seen as the next great civil rights movement. And here come the health officials of a conservative government saying "there's this disease that only targets gay men abs the only way to stop it is for you to stop having sex." And that's just the ones who were permitted to speak, or who risked (and sometimes lost) their jobs by speaking out. There was was amounted to a conspiracy of silence by the American government that delayed public knowledge of and reaction to GRID/AIDS by years.
/* By the way, there's plenty of evidence that attitude is back, even with AIDS-- just take a cocktail of a few pills a day, even AIDS is no big deal! Completely untrue, but there it is. Humans are famous for ignoring danger, even when the information is all right there.
/** The rise of conservativism in the 80s was, frankly, a big part of why so many gay men died. Ronald Reagan killed a lot of the funding for planned awareness campaigns and research-- which simply wouldn't have happened if this epidemic/pandemic had occurred in the straight community. It's why several gay activist groups like ACTUP were founded... to counter, sometimes violently, straight America's passivity/blind eye to what amounted to disease-driven genocide.