Probably because it isn't deadly.
CM Bliss is plenty deadly. No joke ._.
Going to have to run with the general consensus and say Garchomp and Salamence. Garchomp - ScarfChomp and OMFG-I-hate-BrightpowderChomp in particular - I think is more deadly in actuality (having a Steelix helps), but SpecsMence is a bigger problem for my team personally (not having a Blissey doesn't)
TTar is dangerous, but he really has too many weaknesses to exploit.
As for non-obvious Pokes, HaxKiss angers me so very, very much. Too bad it's not over-used enough to be on this poll, but I'd vote for that in a heartbeat if it were.