How extreme is it? I think if someone is trying to post a lot of opinions in a short time that only consist of 5 words then that's fair enough lol but if someone is being somewhat helpful and then gets that then that's NOT COOOOOL
I have seen similar things on other sites, they are to stop spamming or Xper grabbing. In theory you could type out I agree with this then copy it and paste it on a thousand questions in a row then get a 1,000 Xper in an hour. It depends on what the ratio is - Allowing two answers per minute seems reasonable.