There is a centralization aspect in any DNS, blockchain or otherwise in that, literally to be useful, there needs to be consensus about which chain operators own which .{name} extensions for a given name. Which makes financial incentive for say an investor to 'bribe' browsers into using their DNS, which then charges money to end users, which er... feels a lot like the DNS we have.
I think that "true" decentralization might come from nameless "domain". If a domain is a SHA256 hash with no name, then with QR Codes and search engines and hyperlinks it doesn't matter as much that they are not memorable (we managed with nameless phone numbers, right!). Hash providers can be any chain, and then your job as a browser is to add as many mainstream chains as possible (there is no need to decide who is the 'official' one, or rank them, so Ethereum is no better than Dogecoin) as hash collisions are practically impossible.