But you see, that is a result of power centralization.
Feudalism itself is an example of centralized power structures which are tied to another, but its still centralization of power, after all, the lord is powerful because he's tied to the king and the other lords, who all support eachother when a threat to their power comes about, IE a form of medieval corporativism.
That's, not how I would characterize that. Feudal times were truly one of the least centralized times. By definition, it's not centralization if there is more than one center (otherwise you're just making up definitions), and Feudalism was dominated by many centers of power, and not only feudal lords, but also guilds, and the Church, and the town, and the family, and etc. And Feudalism was in general counter to the idea of centralization: feudal lords were the first people to make trouble if there was any notion of their privileges being taken away. And calling Feudalism corporatism when the feudal era was one marked by the least degree of organizing along lines of shared interest is just odd.
So I'll need some sources or evidence on this. I mean this is just entirely new to me. The idea that a system where there exists heavily armed warlords who take tax from the land (and otherwise just leave them be) and all nominally swear allegiance to one warlord or another, and that this is a more centralized system, is hilariously weird. I mean think about it like this: if there exists a group of people with an army who have the ability to challenge your power, is that more centralized or less? Now imagine there's fifty of them; more centralized or less?
I mean look at the HRE for Christ's sake. Does this read "centralized" to you?
Plutocracies come about due to ye olde phenomena of the "friend of the king". Rich businesmen with strong ties to the government can basically walk all over the rest of the private initiative because they get unfair advantages in the "free" market in exchange for favors, which is what happens nowadays with many western democracies. Coupled with corporativism, you get a self perpetuating plutocracy that makes sure to keep a facade of democracy by changing faces now and then, while perpetuating an oligarchy, since only members of the leader's club get to have a true chance at office.
Democracy has yet to find a way to properly stop this from happening, but its still better than any of the alternatives, since there's still the chance the people get fed up and change stuff, which is far easier to do in a democracy than in any other political system.
Look man I'm not here to step on your anarchist theory of society or whatever but if you are going to directly link it to historical circumstances like feudalism, particularly ones that are widely agreed to be a result of decentralization, you are going to need to do some citation. Mind if you had been doing a Marx and using his explanation for things, I'd leave it be (don't agree but it's good logic at least), but as it stands you're going to need to give a little more.
Oh, don't give me that look, the anarchists are over there, with the other hobbits:
You'll find them often arguing with the marxist orcs.
Anyway, that part didn't exactly have anything to do with the feudalism thing. It was just a discourse on how oligarchies manifest on western democracies nowadays.
In regards to feudalism itself, while it was certainly decentralized in comparison to the true monarchies of later ages, there was still a significant level of centralization, with more or less defined hierarchal structure. Lords were expected to answer to the King, and the King (in most cases) had the power to interfere in a lord's fief and even imprison any lord he considered rebellious (hello hello, King John the Landless). Lords also held significant power within fiefs, and could interfere with the affairs of guilds, traders, etc, if they really wanted to. Sure, just because these kind of actions weren't practical most of the time, it doesnt mean they couldn't legally, say, imprison certain guild members over matters of personal interest.
Which doesnt mean true feudal decentralization (practical and legal) was never a thing, as stuff such as the Magna Charta came about. But at the time, this was the exception rather than the rule, IIRC. I'm no historian, so I can't cite any specific textbook sources pointing as to how exactly feudalism worked in all of europe (my view comes from medieval england and the HRE, mostly), but I'm pretty sure it varied a lot, and that legislation in regards to decentralization of power was only put in place later, rather than earlier. Sure, one can argue that practical decentralization was in place long before any actual legislation came about, but I'm also a bit starved for sources on that.