>>50891851I'd go further and say Dark-type moves are actually just moves banned by the Pokémon League, not moves that really share any sort of intrinsic qualities. If we carry this logic further, maybe Dark-type Pokémon are just Pokémon with bad reputations, like pitbulls. I wouldn't consider Dark Pokémon to be banned entirely though.
And this is, mind, just in official competition and at worst can get you an automatic forfeit, not jail time or anything. And I wouldn't say Dark moves are cheating necessarily. Just fighting dirty.