Can't speak for other clients use case (although it seems related to trust scoring and access control leveling) but the aim I have with these is that nostr:npub1updmknky86nsph84rstlh0yymqpeg9l9f62qgxwvd6a75f3pvzxqxv83nv is making children's content so we will want a kidstr relay + client which requires access level amnagment beyond what most clients are pursuing. nostr:npub1t6jxfqz9hv0lygn9thwndekuahwyxkgvycyscjrtauuw73gd5k7sqvksrw has outlined some of the ideas behind getting there in their articles. Multisig (parent/child) npubs + nip5 id access leveling for different permissions types is a good way to manage this.

A few examples could be: 1, #NoorNode uses nip5s to whitelist special otherwise paywalled bonus content from #PodSystems 2, #NoorNode hosts a group chat for SAIF that is nip5 whitelisted 3, #PodSystems uses nip5s for moderator access leveling. 4, we use nip5s for a sisters only relay 5, #NoorNode uses a nip5 to limit access to certain kind/post types on the relay (like only livestreams or articles).

I will stop there but point is there are many use cases for this and it seems silly not to pursue the possibilities.