I thought of something else! I totally would be more comfortable answering a poll about a fic rather than leaving a comment if the fic is way old. Answering a poll feels less intrusive and I think the idea that I'm disturbing the author by commenting on a fic they haven't thought about in a while is the main reason I don't do it. I can think of a whole bunch of fics right now that I wish had had feedback polls because I wanted to squee but I felt too shy doing it 6 months after everyone else had.

And now I'm shutting up, I swear.