Plus flare blitz is easy as hell to predict, and being locked in on it in a tier filled with the likes of heatran, Rotom wash, Azumarril and Tentacruel is eh. It fits in UU though. (damn 420 character limit)
Responding to your sig... Lots of people on the silly things on the ou ladder thread think that Darmy in OU is dumb. IMO, darmanitan isn't stupid, it's just outclassed. SF Flare Blitz works as a great nuke, but it's speed tier is wierd, so it REQUIRES a scarf to do well.