“Since it has been argued so far that an essentially liberal economic regime is a necessary condition for the success of any interstate federation, it may be added, in conclusion, that the converse is no less true: the abrogation of national sovereignties and the creation of an effective international order of law is a necessary complement and the logical consummation of the liberal program.”
A government sans competitors is more likely to refrain from acting to control the economy?
Potentially, yes. A central government may not have competition from other sovereign states, but in a compound republic it would have plenty of competition from other non-sovereign governments.