It’s something marketed as useful but ultimately useless
Discussion
You can search users by their NIP05 on some websites like nostr.band
Meh
If you're using it on your own domain, it can also serve as some sort of verification. For example, you can be pretty sure that's the real nostr:npub1dergggklka99wwrs92yz8wdjs952h2ux2ha2ed598ngwu9w7a6fsh9xzpc
Ok I can see how it’s not quite a shitcoin when using your own domain as it’s a clear way to tell ppl it is you