Not all youkai accept the rules.

...Almost, but not all.

Those who have stayed in Gensokyo for a long time or were never that fixated on attacking humans in the first place approve of the system.

They like this place, so they don't mind as long as they can kill some time.

However, there's more than a few of those who resent living under the authority of the human known as the Hakurei shrine maiden. They feel like they're being forced to protect humans.

They don't care if they have to destroy Gensokyo itself to do something about it.