There are more optimal ways to run our economies than unchecked markets.

Could you expand on that? I'm genuinely curious.

reality teaches us that capitalism has led to oligopoly situations in essentially every imaginable market.

I would argue that America is showing great innovation and increases in their standard of living (note that I am not American, so this is not an America is the greatest country etc. etc. opinion). Microsoft, a behemoth in the early days of computing is now competing heavily with Apple & Google. Apple which took away the smart phone market from RIM is now under intense competition with phones using Android. Everyone is forced to innovate and create a better user experience as a result (see Microsoft's revamped lineup: skydrive, outlook, w8, wp8, etc.). Outside of tech, things continually help make living easier and more comfortable. For example, those automatic shower cleaners and disposable toilet cleaning brushes make it quick and easy to clean your bathroom (especially useful for those uncomfortable getting close to toilets to clean them).

Oligopolies can be beneficial and I would say their presence does not necessarily mean a failure of capitalism. For example, accounting firms that audit multi national corporations essentially need to be an oligopoly. Oligopolies can also have the resources to innovate in a way small companies can't.