The Temporary Containers was a nice add-on built on top of that.[0] While it's a pain in the aspect of cookie-use across domains (like logging into Azure), it's other features out-weigh the initial nuissance - like automatic deletion of the container, as soon as the last one for that particular domain is closed. All of this is, of course, configurable.
This wasn't meant to be a plug, just a happenstance of "if you like 'x', have you seen 'y' based on it?". =]
They're a nice feature, although after a long while of trying, I ended up using just the Facebook container. The main container extension felt like too much work in regular browsing, and the tracking protection seems otherwise adequate when combined with uBlock.
Sadly, Mozilla also seem to promote containers as an alternative to user profiles, while they're nowhere near as full-featured - sharing saved logins and bookmarks between my "personal" and "work" containers is almost never desireable. Managing and switching profiles, on the other hand, is virtually unchanged since the Netscape Communicator days.
That's because you weren't properly setup with containers. I have 4 sessions going on right now, without any manual intervention. Facebook, work, Google and default. All interacting as intended with their assigned domains as isolated sessions.
This wasn't meant to be a plug, just a happenstance of "if you like 'x', have you seen 'y' based on it?". =]
[0] - https://addons.mozilla.org/en-US/firefox/addon/temporary-con...