For what it's worth, I learnt to play basketball in Eastern Europe about 25 years ago, and there was a much bigger emphasis on 3 pointers back then. Pretty much everyone was able to make 3 point shots regardless of their main position.
When I came to the US, I was surprised that people were amazed that "the big guy can shoot 3s". I played center, but it was normal for me to work on free throws, 3 point shots, and also take the shots in the game. I couldn't really understand why players like Shaq were not able to make even free throws, nevermind 3 point shots.
I'm not saying we were all shooting as well as Curry, just that I feel like the emphasis on 3 point shots came very late to the US. It took someone like Curry for people to really internalize just how hard it is to catch up with an offense that consistently gets 3 points when they attack the basket and that yes, it's OK for all your players on the team to be good at shooting the ball.