A government can only exist when it has a monopoly on the legitimate use of force in most situations. How can that, where only one group can use violence without being punished for it, possibly fail to impose a hierarchy?
We can have a government because we can set expectations and behavior. Only when we have police and a state apparatus do we then become a society whose mode of governance is via the state.
I'd say that 'government' would be nothing more than a debating society, like the League of Nations, and just about as useful in preventing, say, homicide as the League of Nations was at preventing WWII.