Stoneclaws are a form of CC, I wouldn't qualify groundings as such - if grounding totems are CC, then you could put priest shielding in the same and to some extent even healing or tanking gear etc. Usually CC is referred to as incapacitating a mob - if its a caster mob which only uses targeted spells and doesn't melee, then yeah, I guess groundings can work as CC.

Not needing CC doesn't mean you outgear the instance. When I started doing heroics i was in 90% blues and I didn't need CC, so i didn't in any way outgear the instance.