I don’t see how container tabs “get you halfway there”? I think they’re far superior to needing to switch your entire browser context to a different profile.
They're not as strong a separation. That said if they work for your usecase then yes they're lower friction by the same virtue. It is very loosely like containers being cheaper than VMs at the expense of some isolation.
Chrome profiles, for example, isolates browser extensions, bookmarks, browser settings, and saved passwords. I haven't used Firefox containers yet but, based on the docs and demo I watched, it doesn't look like it has that level of isolation.
Firefox history is shared among all container tabs. While some of my usage is automatically governed, not all is, hence why I moved to profiles for certain needs for separation
I'll give you my use case. I have 3 profiles, personal, scouts and fencing association. Each of these profiles syncs with its own Sync Profile (email), because they are all used on different computers, some of which are not mine and use the institution email for syncing.
The personal profile use my personal mail, and has various container tabs as needed.
The scouts profile use the scouts email for syncing, share with my fellow scouts.
The fencing association I manage syncs with my personal email in the association's domain, and it has 3 containers: association-personal (for my files and email in google workplace), association-admin (for managing the whole workplace) and backup (recovery email for the workplace and for some other external services before workplace).
With containers only the sync will not work, and also I will be nagged to "switch to this container" everytime I open a google-related page, which I use with 5 different accounts.
Profiles and containers fit perfectly my use case.