You are kind of proving their point here. You are trying to reason with them, but in your mind they are not being reasonable, so you are disengaging because you don’t see how further engagement can be useful. Instead, you just call them the bad one.
This is exactly the process you are arguing against. People are not being reasonable, so you can’t expect reason to be convincing.
Without a central server, hostname resolution is handled with mDNS. It is designed to do exactly what you’re asking: allow you to resolve hostnames to IP addresses without a DNS server. A node simply broadcasts (multicasts) a request for who has a name, and whichever node has it responds with their IP.