No.
It's just to verify that you're you. Stops people from impersonating other people. Anyone can call themselves Mananguri. Only I have access to the mananguri@onlynostr.club account. My NIP-05 nostr address and lightning address are the same.
So for instance, you could prove that you're talking to the real me by sending a 1 sat payment with a message. Only the real me with access to the lightning wallet at my address can see the message you send.
The NIP-05 address of mananguri@onlynostr.club resolves to my npub which verifies this account as the real Mananguri.
It won't matter if you don't set any of this up. You can just leave the NIP-05 field blank.
Setting it up for your own domain is pretty easy. You can even use a free Cloudflare account if you don't have your own website for your domain.
