I'll be honest, I think part of why porn got so up front with the extreme content is because of the internet, more specifically the free tube sites like PornHub becoming more prominent while the softcore genre more or less died out completely aside from the occasional e-thot who does nudes but not much beyond that.
Used to be that softcore porn like Playboy Magazine or the Skinemax movies of the 90's and 00's were meant to be a beginner's thing. Something that pretty much anyone could feasibly find hot, and most guys might cross over into vanilla hardcore stuff at least once or twice, while the guys with fetishes or who were literal coomers had to actively seek out the harder stuff, and this was true even in the era of online porn right up until the late 2000's.
Also, I'd say MindGeek buying up most of the major sites also played a role in this too.
Honestly, porn was a lot like booze.
Softcore stuff like Playboy and Skinemax were basically the equivalent of your run of the mill beers and wines, hardcore stuff was more like hard liquor, and then the extreme fetish stuff was more in line with moonshine or Everclear.
Nowadays, online porn is like going to a liquor store where they got rid of all the Gallo and Miller Lite and while you're looking around, you end up finding paint thinner and kerosene sitting on the same damn shelf as Jack Daniels and Smirnoff.