[hdima]

Firefox also has Multi-Account Containers add-on which is much more lightweight than profiles: https://support.mozilla.org/en-US/kb/containers

[Hello71]

Ah, yes, I forgot to mention that. This is basically Firefox learning from Chrome's mistakes after 10 years, just as Chrome learned from Netscape's mistakes. Chrome added in-browser support to profiles, then Firefox added preference and add-on sharing.

[Flimm]

I don't quite understand your comment. I think you are assuming that Firefox's containers are like Chrome's profiles, but they're not.