I completely agree with you about the abuse of the introduceyourself tag! Whenever I browse through it to welcome new users, there is so much crap there that's not about an introduction at all...
Yes, I think sometimes upvoting your comment is needed if it holds important information in a sea of other comments. People argue though that it's up to others to decide whether it's relevant or not, but on a very active post, you can very quickly sink to the bottom, without ever getting a chance to be seen. That is kind of frustrating and it has happened to me a few times aswell.