Still, it means you must run a lead which can handle Froslass. If you don't, it's going to be even more effective than you say. If you have to make even one switch, there's another layer of Spikes. Now it likely gets 2 layers and a kill, or 3 layers.
And, you know, not every Froslass was a suicide lead. It's not like it can't just switch out and come back in due to it's two immunities and threatening 110 Base Speed or anything. Besides, it wants to block Rapid Spin anyway - especially from pokemon like Claydol and Sandslash who are weak to it's STAB attacks.