All systems have some form of common ground or central point. That does not make every system “centralized”. With the example given upthread, blockchain, there is the development team, or standards organization, which is a central controlling point of the blockchain. Does this make all blockchains centralized? No. In the same way, a common root zone does not make the DNS centralized.
As you note, "blockchain" is a technological concept. Implementations of a blockchain have varying qualities, some of them are centrally managed by an entity, some of them are based on participant consensus in varying degrees. So suggesting "blockchain" be used to solve this problem is a bit like suggesting "nails" be used to build a house. Sure, it's a component you could use, but you haven't really nailed down any specifics about how the house is going to be structured.
DNSSEC, by contrast, is 100% a centralized PKI system. Leaf records are signed up and up and up, and the root of it all is signatures on the root zones by the operators of those zones. Having a hierarchical structure where an entity at the top of the pyramid signs off on the records beneath is about as canonically centralized as something could be.
> DNSSEC, by contrast, is 100% a centralized PKI system.
Again, my point is that just because something can have, or has, a central point, does not mean it is “centralized”. The DNSSEC root cannot override individual DNS records on the domain or subdomain levels. DNS (and DNSSEC) is federated; i.e. it delegates absolute authority over sections to others, which can in turn delegate authority for domains to yet other, which can in turn delegate authority over subdomains, and so on.
To make an analogy again: The US federal government does not possess absolute authority over the states. The UN does not possess absolute authority over its member nations (or other nations). Interpol does not possess absolute authority over every police force in the world. And so on.
Also, the fees for updating DNS records go straight to the validators (people running the nodes) and this list of validators can change over time so it's not a fixed set of entities; yet whoever they are, they always have a substantial personal stake in the reliability of the project.
You don't need to throttle data creation, with PoS, the price of the token goes up with market demand for it. You just need to make the token the main mechanism for payment for purchasing domains and doing zone file updates. This coupling can be built into the code. Many projects have done similar things. E.g. FileCoin coupling token price to storage space.
...Problem with FileCoin is that while it's good for high-read, low-write scenarios (like DNS), it's not so good if everyone needs to update files frequently as update costs become prohibitively expensive. I guess FileCoin could be great for CDN use case.
I really like the concept of Unlimited Domains which lets you buy and own domains forever but I'm wondering why browsers don't support them broadly as an alternative. Blockchains are optimized for high-availability and therefore, that makes them ideal for the DNS use case where you want lookups to be free. Also, it is acceptable for updates (e.g. ownership changes or changes to the 'zone file') to incur a cost that is proportional to the utilization of the network for that purpose; it would guarantee that each update action would incur the lowest price possible.