This doesn't make a whole lot of sense. Sure, anyone can create their own root zone. I can create my own .com zone too and point my resolver to it instead. But

This doesn't make a whole lot of sense. Sure, anyone can create their own root zone. I can create my own .com zone too and point my resolver to it instead. But what use is it if it doesn't contain useful entries that point to things I want to access? What use is it if all the parties underneath it aren't sending me updates to the zone? Someone has to do that job for it to all work. Do the managers of the hundreds of TLDs around the world contact you to update your version? No, they send them to IANA. The IANA's job is simply to be the authoritative repository of unique identifiers and associated configuration data — TLDs, IP addresses, port numbers, MIME types, etc. You are free to use your own bespoke IP addressing scheme, port numbers and MIME types too, but don't expect to be able interoperate with anyone else.