You misunderstood what I said. DNS is certainly a decentralized protocol and obviously not at all necessarily DIY. That’s all I was speaking to. Decentralized can be that simple.
What you originally said could be interpreted as either DNS-the-system or DNS-the-protocol. I assumed the former, since that seemed more likely.
Sure, the protocol could be used without the resolver hierarchy, but I would argue that's not a useful way to think about it, since it won't happen in practice.
You can run your own name server, but there's no good way for large numbers of people to voluntarily opt out of the existing system.
https://en.wikipedia.org/wiki/Root_name_server