People do it because if they say something negative and they don't say that, people on the board will just assume they are a UK hater or a fan of another team. So people feel the need to qualify it.
For example, I think UK loses, but I hope I'm wrong
If I just say I think UK loses, I'm perceived a hater
If I say I think they lose but I hope not........then it's like how it's intended to be in the first place.