That's like saying anyone could open their own Facebook, and therefore Facebook is not centralized. The DNS is centralized, even if domain names are used in co

That's like saying anyone could open their own Facebook, and therefore Facebook is not centralized. The DNS is centralized, even if domain names are used in conjunction with decentralized protocols like TCP/IP, and even if anyone is free to create their own instance of a DNS. The only sense in which it's decentralized is in relation to the legal right to operate one. It is a free market institution, instead of government-instituted monopoly.