The users registry is maintained in the protocol to carry out various tasks such as stopping channels from adding them again (after a user has unsubscribed), if their public key is in the registry, what channels they are subscribed to and a mapping to get to those channels, if they own a channel, etc.
- If the user is already in the ecosystem
- If their public key is already in the registry
- Whether they own a channel
- The channels they have subscribed to
- The channels they have graylisted