Cronyism can exist in an economic system where there are positions of power. However, if you were to limit position of power, I believe you could make an economic system more resilient to cronyism. Obviously systems like the USSR had positions of extreme power so it was very prone to cronyism.
The US Constitution tries to do that by pitting different groups in power against each other, diffusing their power and forcing them to cooperate to achieve anything. And then adding a Bill of Rights specifically limiting the power government has over the individual.
Do you have a better idea?
[0] https://en.wikipedia.org/wiki/Mutualism_(economic_theory)
Try reading the article?
[0] https://en.wikipedia.org/wiki/Mutualism_(economic_theory)
Capitalism is a great platform for cronyism because it accumulates huge amounts of wealth in one place. Without capitalism the wages of corruption would be much less.
Institutions like contract law and constitutionally limited government helped the reign in corruption to some extent. If corruption is to mean deceit, abuse and exploitation, corruption has existed since as long as humans have existed. That is why homicide rates in prehistory were 30%.
When people consider your ideology "natural state of the world", you know your propaganda succeeded.
Capitalism is private ownership of (and thus control, and benefit from) the means of production. Of these things you've listed, only corporate stock is—at some remove—a means of production. The stockholder owns part of the corporation which in turn owns capital goods.
Anyone can save and invest and become an owner of capital. The only thing leading to concentration of wealth (under any economic system, really, not just capitalism) is that most people don't care to sacrifice present consumption for a larger future gain. Fortunately there are some who do.
Now, that obviously doesn't happen in all areas all of the time. And we have moved away from that kind of rules-structured ideal over the last forty years or so in pursuit of greater efficiency (which has re-introduced cronyism in the UK to a greater degree, for example - see the present government) but it's grossly over-simplified to say that cronyism is an 'essential' part of big government, when its original foundations were intended to produce a (big) government of laws and not men.
Edit: the problem is kind of moral hazard. Much like a chemical plant or nuclear reactor needs a range of protection systems to prevent the dangerous chemicals from going out of control, public administration needs a range of systems to prevent corruption getting too out of hand.
It's not just a public admin problem, either - corruption and self-dealing are potentially endemic in the private sector, too. The concern has traditionally been higher for the public sector, both because of the potential for abuse of state power and because it is/was seen to be corrosive to public trust and self-government. A private company is more likely to trade off the cost of controls versus the dollar value of the future loss (or the controller is the one running the firm strictly for their own benefit, in which case they're likely to get away with it without intervention by the legal system). And the largest companies have had actual public power greater than the smallest countries for centuries by this point, so the two concerns are not completely disjoint.