Be slightly careful with Wikipedia about Rome. Such sweeping generalizations covering hundreds of years can't be always accurate. In fact the Senate's power waxed and waned depending on the politics of the empire. Under Claudius, the Senate was comparatively powerful if largely to convince everyone that the days of Caligula were over.

Understanding the dynamic nature of governments, especially ones as expansive as the US government, is necessary I think to appreciate how little democracy we actually have in the United States as it now stands. If we want to pin things to the definitions historians use to differentiate the Roman Republic from the Roman Empire, I think we passed that point with FDR to be honest.