It sort if have to be. In the end there has to be one source of truth for each TLD, otherwise who is to say who owns foo.com, and what it resolves to?
And then the same structure for assigning TLD ownership.
But there is nothing stopping you from running another DNS service, call it DNS2 with different root servers, etc. It is just going to be extemely hard to convince people to use it.
Eh, git is good but it is not like he invented source control. Before git there were subversion and before that CVS, along with a lot of others (mostly pay to use).
Git does some things really good and has become more or less the de-facto standard, it does other things not so good (like binary files). But it is not unique.