Correct. You can copy your SD content from one card to another but the saves are stored locally, which, as far as I know, you can't access.
Nintendo's explanation revolves around people abusing/cheating with cloud saves in games like Splatoon 2, Dark Souls and Pokemon. For instance in Splatoon 2 you could lose progress with a bad run in game, then exit the game and reload the cloud save to gain it back again. There is more to it than that (look up some of the creative ways that Dark Souls players abuse cloud saving on PC). I'm not convinced that they can't find some sort of compromise and maybe one day they will. For now, it is what it is.