I think opt-in ID is great. Services like Discord can require ID because they are private services*. Furthermore, I think that in the future, a majority of people will stay on services with some form of verification, because the anonymous internet is noisy and scary.

The underlying internet should remain anonymous. People should remain able to communicate anonymously with consenting parties, send private DMs and create private group chats, and create their own service with their own form of identity verification.

* All big services are unlikely to require ID without laws, because any that does not will get refugees, or if all big services collaborate, a new service will get all refugees.