Not having a CoC doesn't mean you don't address bad actors, resolve disputes, etc. It just means that these things are entrusted to the project leader's best judgment. And anyone can fork the project if they think the project leader isn't doing a good job of keeping things orderly.
It's a matter of scale. Humans have thousands of years of history codifying rules for communities. From Hammurabi to your HOA, people have found its easiest to enforce rules when you write them down.
