Well, sure, and sabotaging the button for submitting a comment so that half the time it does not do anything works the same way. The point is that for a <i>given volume</i> or rate of new comments, the moderation burden of a comment is the same regardless of the age of its parent -- provided, again, that the moderator&#x27;s method for finding out about the next new comment is O(1).<p>Note that I&#x27;m not claiming that old comment sections should always stay open forever, just that great grandparent is not on its own a good argument for closing them.<p>So here is a second argument: maybe the site&#x27;s moderation process relies on flagging by ordinary users, and maybe the modal ordinary user cannot be coaxed into using any method for finding out about new comments except for scanning individual comment sections.<p>I jumped into this conversation because I suspect that it is worthwhile to try to keep comment sections open as long as practical, so if I were in charge of a discussion site where the assumptions of the second argument were valid, I&#x27;d try to avoid the conclusion: for example, I might give users a way to subscribe or express an interest in getting a notification (by, e.g., email) whenever a new comment appears in a particular comment section; then I&#x27;d keep a section open for new comments as long as it has subscribers; and then I&#x27;d wait to see whether the subscribers flag enough of the new spam in the section to keep rate of spam in the section to an acceptable level.