99% of the time or more, it is used after one person gives an opinion. It is rarely, if ever, used after anyone has proved or disproved anything.Only if it is a stupid post. If it is indeed salient and satisfies the OPs main argument or disproves it, then it is still appropriate.Stating your stupid opinion and finishing the post with "/thread"
It takes a pretty stupid person to think they've got the final answer.