I agree. Much of what we see here are small, disconnected comments. Therefore, were I to delete all such comments I might as well forbid people to comment.
Which is why I do not see any reason to keep deleting comments. Only those which significantly disturb the rules (Profanities, serious spam, gratuitous rudeness, so on, so on.) Therefore, I shall restraint my self to that which might disturb people and keep reminding people to avoid replying to comments older than 2 weeks, and absolutely try to avoid to reply to comments older than a month.