If I remember the documentation around the decision to switch correctly, having enforced sign-in for moderation was on the requirements list.

EDIT found it:

> While we’re investigating options for semi-anonymous or pseudonymous connections, we will require authentication, because:

> The Mozilla Community Participation Guidelines will apply, and they’ll be enforced.

http://exple.tive.org/blarg/2019/04/26/synchronous-text/

(Don't ask me why the article seems to pretend IRC has to be unauthenticated)