If I've paid for a piece of sheet music and my discord group says "hey, can we get a link to it?" I might not even think twice about just posting the link to the url. But if I actually have to upload it to some file sharing website and then post the link to that url, I've really made it clear to myself that I'm sharing something that shouldn't be shared.

Obviously they're the same thing, but I feel like adding barriers to sharing probably does reduce them somewhat.