It's for fun.

"URF is for fun, don't surrender."

Well you're right but you're wrong. Yes, it's for fun. That doesn't mean you don't surrender. In Ranked you don't surrender because there's a chance you'll will and you benefit from it with LP. In URF, you don't lose anything from surrendering. When you stop having fun, you stop playing. Simple as that. "Oh but I'm fed, you three just suck." Is like telling everyone you won't drive them home after they've all thrown up at the beach.