I appreciate what you're saying.
But I'm using this more in the context of potential security. Promoting an inactive user to a more restrictive group is a good use-case for this. In my case, I'm not talking about being inactive for a week. I'm talking 180 days. Half a year. That's more than enough time to await a response from a member. I'll be the first to admit, I'm a pack-rat. I have a hard time purging members, because there's always the possibility that they'll pop back on. Placing a dormant user in a demoted group like this also advises other members that, "You probably won't receive a reply from this member".