Two powerful competitors frequently end up locked in a stable, mutually beneficial dance of tit-for-tat—they collude, in short, to carve up a captive market.
It's always nice to see an article that explains some basic concepts of industrial organization (IO). And though this one is set in the context of our political duopoly, its political implications are actually far broader.
The very idea that a stable duopoly (or oligopoly, for that matter), operates to the detriment of consumers is revolutionary. It underlines the fundamental problem with labeling particular political stances as "pro business." And if you play it out a bit, it explains why the politicians who truly deserve to be labeled as shills for big business are those--like Henry Waxman or Barney Frank--who emphasize expansive, complicated regulations.