When I comment on an old thread on HN, it's probably because I haven't noticed that it's old, because I agree there's not much point commenting on a thread wher

When I comment on an old thread on HN, it's probably because I haven't noticed that it's old, because I agree there's not much point commenting on a thread where your comment is unlikely to be read by anyone. On Reddit, where threads seem to hang around for longer, I might comment on an older thread if I think my response will be helpful to others, but not just to voice my opinions.