It happens to me a lot, but it doesn't bother me. Here's why:

I enjoy the process of searching for and finding obscure songs, the same way some people enjoy solving crossword puzzles. (Nobody thanks them, either, yet they keep working at it.)

I enjoy it so much, I even go searching for unanswered requests in very old threads. Then I try to answer them. I realize from the outset that there's practically no chance that the original requestor will come back and see the answer, but I enjoy it anyway. If someone thanks me, that's a bonus.

I find Allan Whittle's message very interesting. I suspect there are a lot of people like him, but we have no way of knowing.

I also suspect there are a lot of people who come back but don't know how to find the thread again once it has dropped off the front page.