I certainly agree with your last point and your characterization of modern economic elites. It is however difficult for me to distinguish it from the past, partly because some ancient societies, which lasted longer than our present day constitutional republics, such as the Roman Republic and the Athenian democracy, enjoyed mass participation in politics that managed to keep the various elites in check much of the time. Beyond Pol Pot and Cortez, Carthage and Taranto, I can't think off hand of any wholesale massacre of the local elites. And all massacres were perpetrated by invading armies or rival elites. As for the gradual collapse or transition of the Western Roman Empire, there was no elimination of the elites. They were perhaps just as dumb and parasitic as their modern heirs and got along on expedience, corruption and private armies.
  Elites, through greed, stupidity and banking on immediate short-term gratification, always owe their acquired intelligence and skills to a social contract with the commons. Without an institutionalized conflict between classes there is only brute tyranny, indiscriminate oppression by the one class that can afford the costs of violence management.