King: Yes, I was a threat. So was Rome when Caesar started conquering Gaul. But did they go and assassinate every single Roman governor and general Rome had back then?
Vercingetorix didn't even manage to kill those leading armies (Caesar, Mark Anthony...). Here they just decimated my characters at insane rate.
That cost doesn't have to be high (like 250 for bribing a governor). But there should be some cost because the level of spam is just way too big now. Please try it for yourself or at least tell betatesters to try it (border like 15 factions, go over BB limit), you will see how annoying this mass murder is when you get 10 popups each month about caught enemy spies. I'm sure it will convince you.