I get that it’s not ideal but I think it’s worth keeping in mind that there’s not much you can mess up with it other than refusing to update requests. The threat model is very limited and it would immediately be obvious that this is happening, killing the credibility.
ICANN is a severe risk btw. Current new protocols should be designed to avoid DNS wherever possible.
At the end of the day, truly fully decentralized systems are literally impossible, there's always a centralized aspect (at least for bootstrapping) and it's usually DNS-shaped.
That being said, PLC directories are a problem that blockchains (yuck) actually solve very well: trustless, public ledgers. I would not be surprised if we see a separate implementation based on an architecture derived from such systems.