—One big lesson in politics: people oppose a faraway government because it isn’t “theirs.” They see every act of the government as a usurpation. When people get a government that is “their own,” they tolerate and even demand the same kinds of things they objected to before.—
It is because they exercise more control over their local government. They are also more accountable.
So people say.
But that goes against the libertarian argument that revolutions and secession movements are against intrusive government and dependence on politicians as such.
Rather, people just want to feel they have more control over government. When they get that they're not as opposed to taxes on "the rich," subsidies, welfarism, and bureaucratic regulation as their earlier rhetoric might have suggested.
After the Revolution we taxed ourselves more than the British tried to tax us. It would have been the same with an independent South.