Wonder if it's a poor interface issue... if people could just click a button that says "me too" but didn't add a full comment but rather just added some minimal notation at the bottom of the comment that indicated their username, 1) would people use it and 2) would that be not overly-busy enough to not be annoying? It could even mute notifications for the me-toos.

This seems like an area where LLMs would actually be extremely useful. You can manually mark comments as irrelevant. Why can't GitHub use AI to do it automatically? Or to highlight the "resolution" comment automatically? On very big issues it can take a non-trivial amount of time just to find out what the outcome was.