By the only ones that tell us stuff. You making up stuff inside your mind doesn't make it a valid argument.
The world of AoT can't be compared to our real world 1:1 and you know that. The whole world saw what titans can do when Marley conquered them. They, EVERYONE, want the titans gone. Afaik they all expressed their hatred toward titans. Killing Marley leadership won't remove the world's fear of Eldians. It's irrational, like our real world's hate towards innocent pedophiles: The moment the word "pedophile" is used, people lose all their IQ and become dumb. "Kill them!", "Castrate them!", "Monsters!" - towards innocent people who have never committed a crime. And no, hardly anyone makes a difference between pedo-criminals and innocent people who just happen to have a pedophilic attraction that they don't act upon. This is what it's like with Eldians: Them promising not to attack the world with their titan powers wasn't enough for the world. Thus the world tries to eradicate all Eldians. And that is a sentiment not exclusive to Marley.Hey numbnuts. Guess what happens when you liberate someone from their conqueror. They don't stay conquered. See: Poland/France/North Africa/etc. After the Nazis were defeated, those countries didn't STAY Nazi controlled.
The whole start of season 4 shows Marley at war with these other countries. If you get RID of Marley, those countries aren't just going to keep on towing the Marley line.