If the queue size grows beyond volunteer capacity then volunteer time becomes a scarce resource. In my experience (in other organizations), more likely than out and out block listing is aggressive prioritization. It takes sensible design to determine which papers get to consume moderators' time first.

Then, if someone posts rejected papers regularly and is deprioritized, it naturally follows that they may try to submit three more... and get stuck naturally. There is no need to ban them. They will still get a response, and they will get a fair shake - when there is time.