Don't be stupid. Of course it happens, and it happens as often as people brigading 1's.
There exists groups of people who blindly champion a product and give it 10/10 for the sake of boosting its rating just as there are those who put 1's to bring it down. And you even bring up a strong example of that with WoT.
As someone summed it up nicely above, most people who watch don't even bother reviewing. Fans and haters are much more likely to care enough to give a review than the average casual watcher. And shows with large fandoms and shows that have something controversial tend to have their reviews swayed by both tribes.