It helps people easily verify that it's actually you, since we can't easily remember npubs and someone could try to impersonate you.

Your npub is associated with beave@ok0.org (for example), and I set up ok0.org to vouch that beave@ok0.org is indeed your npub. Clients will show you as having a tick, and any impersonators will not be able to have this verification so they will be easy to spot.

If I see a The_Beave posting, I can easily tell if it's verified as beave@ok0.org or not, at least that's the idea. as nostr:npub1njst6azswskk5gp3ns8r6nr8nj0qg65acu8gaa2u9yz7yszjxs9s6k7fqx says, it shows gang affiliation and it's cool lol