Current system does have many nodes in a hierarchy but they are operated by trusted entities and there is not much fluidity. Also nobody owns their domain names; just renting from the centralized providers and you just have to trust them with everything.

With a blockchain, you would provably own your domain name and nobody would be able to change your 'zone file' aside from you since they wouldn't know your private key. I mean it would be physically impossible even if they wanted to do it illegally (or if the TLD operated under a crooked government).

BTH, this has already been done by Unlimited Domains (.eth TLD) but for some reason it still hasn't been integrated into major browsers (aside from Brave which has it disabled by default though it definitely works).