True, but the way he does it is terrifying. Literally anything you drink could be laced with the stuff. If Arkham is any indication, he doesndoesn't even need to give people much incentive. How frightening is it that Gotham has not one, not two, but at least three villains with a compound that can a) scare you to death, b) make your corpse look like the Joker, or c) Control your mind to do unspeakable acts?
Yes, Tetch is mostly useless, but he HAS won a couple times (never against bats, though).