I think you're missing some important details in your definition of centralization. It's not who uses it, but who controls it.
That is the power of decentralization, regardless of the naysayers and corporate shills who continue to dismiss the whole concept, by citing examples of alpha-quality solidity contracts. Ethereum, despite being itself barely beta-quality, and highly primitive technology of its kind, is still a disruptive technology that threatens the status quo. Creating an app that has the strengths of Wikipedia, but functions like Google, Facebook, or Twitter will be an order of magnitude easier with the help of this technology, and the right team. Maybe not enough to disrupt things outright, but certainly enough to be a large threat, and the next generation of that type of technology will have a near-guarantee to bring that disruption. Obviously there is a lot of vested interest with deep pockets, toward discrediting it. The resulting narrative, combined with the consumer culture/sentiment toward the products by the same companies, is what makes up the centralization culture. I think we need a catchier phrase, maybe even a buzzword to describe it :P
Don't get me wrong, I think many crypto enthusiasts out there are insufferable man-children with criminal records and an axe to grind with "the man". So blockchain's culture might be the problem in the sense that some of the users are giving the technology a bad name.
Open-licensed content cannot be said to be controlled by one party, as anyone is legally entitled to create a fork. Thus, Wikipedia is not controlled by the people who run the servers; the infrastructure may be centralized, but the project (the compilation of knowledge, and the articles produced) is not. This aspect of control is what I said you were missing in your assessment, and it seems I was right.
Ethereum is a platform for creating decentralized applications, and it too has technology and policy that is managed by a central foundation. That doesn't mean that the ecosystem is centralized.
Zooming out, we can see that the Linux Kernel development itself has a centralized development model, even with a dictator in charge. But the Kernel is a platform for which anyone can create and ship a distribution on top of. As a result, I am able to enjoy the use of three or four distros (or more, if I wanted) that are most tailored to my use cases, instead of being forced to choose between Pepsi and Coke (Windows and OS X). And many people can get into operating system development as a hobby, with a much more achievable criteria to do so.
We can zoom out even further: The FOSS movement itself might not have existed without the relentless efforts of a few individuals over a span of many years. But from day one, the ecosystem it spawned was decentralized by design.
Going back even further, we can show that market Capitalism allowed for a rapid and diverse pace of technology and business development. Less barriers to entry. Less red tape. Obviously we have had governments, both big and small, to facilitate the economies of a nation.
What do all of these things have in common other than incorporating applied forms of decentralization? It is not just a buzzword. It is no coincidence that these frameworks have (or will) foster significant societal changes, mostly in good ways. That's not to say that the success rate is high for any given effort, but it is not a concept to be written off, especially not because of a lack of understanding of it.
The problem is that most people, even here, cannot visualize this concept in ways that they have not seen working examples of. Not a problem, not everybody is exactly a visionary in every way. But when people are actively trash talking ideas that they don't understand, without offering constructive opinions toward an understanding of it, then as technologists we ought to be taking a stand against that behavior.
Instead, what I see in many cases is that many engineers, for whatever reason, will write off certain technology ideas, believing that they understand it, when they do not. I was one of those people, for years, so I understand the mindset as good as anybody. Or perhaps they saw too many uninformed comments coming from non-technical crypto enthusiasts, and therefore have written off the idea. Folks, if this describes you, I encourage taking up the study of critical thinking techniques. The world deserves better than to have such a large number of engineers not giving the discussion a fair shake.