I'll give you four examples
1) this, a user commented on my question, he solved it and then someone else 2 hours later, said the same as an answer, although I'm so grateful to all the members in this great community, I don't know if I should give the guy who answered any credits/reputation, the guy who commented might think it's unfair and i think that.
2) this, I haven't had time to test the answer, should an answer be accepted, if not tested by the asker?
3) this, I don't really know common lisp, so I don't know which answer is better, I upvoted all anwers without accepting any.
And the last senario would be if I'm asking for an opinion, lets say on Chess.SE, I asked which opening is better and I got more than a great answer