I'm surprised raiders haven't decided to intentionally create a region with 50000 puppet nations just to attempt to crash the game during an update. I'm sure something of the sort will be attempted eventually. Maybe I will just to prove my point. (This is sarcasm/extreme hyperbole, not meant to be taken literally...)
Edit:
Oh look here, apparently puppet flooding is already against the rules:
NERVUN wrote:Puppet Flooding: Any player or group of players creating large numbers of puppets for the purpose of spamming and/or annoying a region, be they invaders, defenders, or natives, may find all such puppets ... and their main nations ... deleted without warning as Regional Happenings spammers.
Can we get the puppet-only spam regions deleted now?