-If you don't like it, why are you still watching it? -You've only watched the first minute/episode/season, you don't know what you're talking about and it's still too early to judge!! Every fandom ever.
But it's so much fun to watch something and then complain about it even if you secretly enjoy it. And a lot of people like to jump on the bandwagon even if they haven't seen a show. I watched the first season and a half of Game of Thrones and by that point was deeply disturbed and I was sure it wasn't going to get any better, I hated it.
Technically if someone's only watched a single episode or a couple of minutes, then they aren't part of the fandom. It might also be that someone is a fan of the subject that the show is based upon, and as a fan of the original source material, they strongly feel the need to express their disappointment. In that case, they do know what they are talking about and do have a right to criticize.