The fact that you can't fail makes a big difference, as well as the super easy modes.
So if your playing say a long mystery setlist, and in the middle a super hard song pops in. At least you can struggle through it and finish your set.
I was playing a 3 song suprise setlist on X drums. Some of the top tier songs really kick my butt. Got Rio on the second song, failed like 5 or 6 times but finished it with 1 star and like 10k studs. But at least I got to finish the set.