It killed off many quality series far too early, like Pushing Daisies, Firefly, Dead Like Me, etc.
Firefly was killed off by Fox who never understood it in the first place. They showed it out of order, gave it an unpopular timeslot and demanded a mediocre “action” pilot be shot at the 11th hour. The advertising for the show was misrepresentative – it was billed almost as a farce – and they almost shitcanned the entire thing in the first place because they didn’t approve of Wash and Zoe’s interracial marriage.