Rebels objective is to stand on roads, hide and gather forces, then harass (any) armies. Rebels don't take part in wars, they have no allies just enemies, but if a town riots, they'll try to capture it. Rebels are a pain in the ass, not just plain ass
(In a nutshell: I won't be able to win as rebels and I won't even try to take over anything without it's settlers rioting. I'll be just an extra, so it's more realistic. )