The problem is you have people that refuse to admit that someone else is correct, even when someone clearly sources a correct citation. This isn't always the case, as (believe it or not) there is something called opinion. However, some opinions are just really not correct. For example: "I think that all muslims are terrorists and should be deported". Yes that is an opinion, but every single piece of evidence goes against what you are saying. A 'correct' opinion could be, "I think the risk of potential radical terrorists getting through screening is dangerous, and therefor we shouldn't let any immigrants in." That makes sense, the other one does not.
People need to realize when they are saying things that have absolutely no proof or evidence behind it, and be able to back down from their opinion and admit they are wrong. It's a difficult thing to do, but it's only way we can have completely fluid arguments without bitching back and forth.