What's impractical about everyone having a domain name? It surely isn't due to lack of domain names, because foo.bar.baz.bim.bim.bap.com is a valid domain name.

It is true that full data sovereignty isn't something most people are interested in, but this is more about a cooperative model for data ownership and access. Having your data identifier be JackDaniels@yahoo.com isn't particularly different from it being jackdaniels.is.technically.bourbon.com. In both cases another organization owns some of the path to your identifier and could potentially lock you out of it. In both cases, verizon is near the top of that list (.com).

As far as the domain name system being centralized, I'm not sure I agree. DNS is like a feudal system with hundreds of kings (top level domains) who all work together with one pope (ICANN), and various lords and ladies occupying positions under those kings. If ICANN goes completely bonkers the kings can get a new pope, some of them are literally sovereign because they are nation states. Just for fun, some of those states are ruled by literal kings, too. There are experiments to run a TLD by Decentralized Autonomous Organization (DAO), but I think for the most part nobody really cares because the current system happens to work pretty OK. If you have an idea for a more decentralized way to organize a namespace that doesn't involve your grandmother typing in a massive UUID or onion address, and doesn't result in someone being able to domain squat literally everything; I would love to hear about it.