A world government could be libertarian in the short run. However, if it were to gradually become authoritarian, there would be no escape, and no comparison that one could make to other societies. This would only encourage authoritarianism.
And combine that with the oligarchical tendencies of governments that have massively huge numbers of voters per representative. Any benefits of democracy are lost in such situations.
And combine that with having a World State cover vastly different cultures across the globe. You'd be including millions of people who may be culturally predisposed to accept dictatorship or theocracy. How would freedom-loving people on the other side of the globe be able to fight that democratically?
There are many rational and practical reasons to oppose the World State.






