If stealth rock is banned then I can see a shit storm impending about things like articuno being broken. Stealth rock is just too important to ban, you can always use taunt magic coat or rapid spin to keep them off the field, I really don't think stealth rock should be banned but we'll see.
Except the problem with spinning to keep them off the field is there are hardly any spinners in this tier, and the only decently usable one is Kabutops.
And Articuno would be far from broken in this tier. It's attack stats are only average, and it is weak to fire, electric, rock, and steel, the first two of which are fairly common attack types. Heck, Magcargo of all things wall this guy beyond belief unless Articuno runs Water Pulse, but that's a waste of a moveslot.
Overall there's just too many Pokes down in this tier that would love to be used but are completely stopped by, in essence, the unstoppable power of Stealth Rocks down here. This meta is going to be centralized around that one move, and when you have to devote two slots to stop it (one to spin, one to kill the SRer), there's a problem.