Once again, I blame the Chicago school of economics. Fuck that economic theory. It's exactly why we have the mega corporations of today, it's entire purpose was to neuter the Sherman antitrust act after Roosevelt's crusade against the trusts.
the chicago school is just a natural development of capitalism. In competition instead of cooperation, the winner absorbs the looser and cetralizes production more and more into oligopolies. Even if you turned back the time before the era of "crony/coorperate capitalism" it would take but a bit of time to get back to the state we are in right now...