sort of. it was a nuts and bolt implementation. by their own admission it was reintroduced to make it more friendly. from a comment I saw made elsewhere:
> yes about:profiles has existed for a long time. We have heard feedback from many of our users to make it user friendly and accessible. We are introducing many new additional functionalities in this new profile management experience (avatars, colors/themes, shortcuts, desktop icons, default links/apps per profile, copy profile, move tabs between profiles). Stayed tuned for these updates.
Profiles have been there for years, been using them since at least 2010.