[LinuxBender]

If anyone can give me a technical explanation why it’s impossible to host your own nameservers or have your own custom domain, I’m genuinely curious.

Anyone may host their own name-servers. I run many of them for my various hobby domains. I can add any TLD I can think of however for someone to query my name-servers for those domains without them first manually inserting logic to query my name-servers would require the root servers to recognize that TLD and have entries for my name-servers. To get a new TLD into the root servers is not a technical problem at all. It is a governance/regulatory obstacle and very extremely non-trivial to jump through all those hoops. You asked for the technical explanation. There aren't any technical limitations to my knowledge. Technically the root server operators could add anything that conforms to the DNS RFC's.