I understand that a separate thanks isn't useful for answers to your questions, but in comments, you're often asking a specific question of one particular person (as opposed to anyone who reads your question and has time / inclination / ability to answer), so it seems that a thanks is more in order.
I could just up vote the comment, but how would the commenter know that it was I who upvoted the comment and not someone else?
It seems more human to leave a comment, but it seems better for keeping the noise to content ratio low to merely up vote the answer comment.
What are your views on this? Not leaving a final,
Thanks! comment just seems so cold.... even though, leaving it definitely increases the noise to content ratio.