No one needs to be governed as long as all their neighbors are "decent" which I think means "don't behave in a way that impinges on what I want" But that is never the case. Most often decent enough people want to have the freedom to behave in ways that make it impossible for other people to behave in the same way. For instance if everyone wanted to subsistence hunt, we'd run out of game.
The problem isn't that governments exist it is that they don't die. Colonies of cells collaborating to make a human do better than single cells, but eventually things go haywire and the human dies. This is super important to allow the next generation to try to do better. We need more space for people to try new ideas without being smothered by 200 years of law.