Low star or low AR?

So there is an idea I've heard in a lot of places (digitalhypno's osu phd is a big one) that to improve your accuracy / consistency you should play low star maps more. What I don't get is if it's about them being low AR (which I find insufferably tedious to play) or about the rythms being simpler. So I figured I'd ask here what you thought about it.