I'd say it's a loophole.

His post is on topic because he gives his opinion to the @OP's post and it's constructive as long as his post has a weight, right? not to mention few campaign managers consider a long post without any point is constructive.

But we as a reader find it's not good since read someone post that repeating a same point that has been mentioned by other user or asking a question that has been answered by other user isn't make any sense.

Honestly I don't really care if it's a newbie or user without signature, but for someone who join a signature campaign, I guess there's need an action.

Yeah, it happens a lot especially in Altcoins board.