I've read about when notifications are sent from comments, as stated in this question: When exactly do I get comment notifications?
However, sometimes I like to know when others upvote my comment. It tells me that others are thinking the same why I am, and while I don't think it's deserving of reputation, it gives me confidence that my post is being read and that others agree. In addition, I am more likely to follow up on a comment thread (that I am not being constantly tagged in) if my comments are upvoted, but sometimes it is easy to forget a comment you left on a post, and it is sometimes hard to go find it again (a meticulous process just to see if it has any upvotes).
I understand that notifications can sometimes be a logistical nightmare for systems like SE, but would it be feasible to get a notification when your comment is upvoted? If not, what would be the reasoning behind such a decision (not that I necessarily disagree with it, just wondering)?