In the Metagame, you'll be surprised that more people would run Poison instead of Steel coverage against Fairies. Probably because one of the more dangerous Fairies is Azumarill and it's not weak to Steel. (As for Mawile/Klefki? EQ/Fireblast takes care of those)
Yep, Poison actually one-upped Steel in terms of anti-fairy moves, and thus made Steel's SE against fairy non-existent for coverage unless it's STAB.