Curry would struggle in a more physical era, with hand checking and less favorable rules for offensive players. People forget that the rules have changed over the years making it a lot harder to play defense. Curry wouldn't be trash in the 80s but he wouldn't have nearly as much freedom of movement as he has now.
Also, as Bill Simmons brings up a lot, the injuries that Curry had really his career would have ended his career in the 80s. Medical advancement has made his recovery possible.
these comparisons between arrows are impossible because we're assuming that you just dropped Magic Johnson from 1983 into 2019. Realistically, Magic would have been ruling to shoot 3s in HS if he grew up now