I think that libertarians are just as utopian as the social anarchists. Actually there are probably far more historical examples of anarchism — just not in post-tribal society. Just as contemporary society (or even going back over a thousand years) society has not been organized decentralized via horizontal collectives, I don’t think there has been a single example of capitalism that was not of the crony variety. You can’t eliminate corruption, I don’t think, although you can tamp it down.
When you have large successful corporations/businesses, invariably you have government tied up in their activities. They have probably been corrupted by business — to work hand in glove with them — but there have been populist and reform periods in history, where government(s) have sought to work for a wider swath of folks. They have actually cracked down upon unscrupulous business practices, and the middle and lower classes have benefitted from this; and this is illustrative of the type of situation through education and activism that can be developed once again.