Two types of people are called critics. Only one deserves the title.
The first type offers insult without substance. She’s the faceless heckler up in the nosebleeds telling you how much you suck. This person is not a critic, she’s a troll, and can and should be ignored.
The second type of person, a true critic, offers specific insights into where a creator came up short in either design or execution. This is a valuable service, though not nearly as enjoyable to be on the receiving end of as a massage or a haircut. A thoughtful, erudite critic can help a creator identify and shore up weaknesses and produce better work. For this, creators and fans alike should thank the critic; like the law, he should be loved a little.
Dismissing trolls is vital. Doing the same to all critics is hubris.