They're quite practical even if you don't care about tracking. I have different containers for my work and personal Google accounts and they make things much easier than relying on Google's support for multiple accounts.
They're also great for development. I have different containers for each user I use while working on logged-in flows. I can just go from tab to tab to test different user experiences or switch between users in a multi-user interaction.
This is one of the things I used to like IE for - perhaps the only thing it got better than the competition:
File | New Session
... and then you have a fresh session context that doesn't share cookies with the others so you can log into services as different users. As a developer this is very handy for testing multi-user workflows, and had numerous uses as a more general user too, and it was easy to do ad-hoc without needing to setup multiple profiles first.
It didn't work for apps that are sensitive to permanent cookies (and other client-side storage) instead if session level options of course, where multiple profiles does (as presumably does Firefoxes containers? - I don't know as I've not yet used them).
That does sound useful. I often end up creating several temporary containers while doing testing and development. The overhead of creating and deleting these is annoying.
Yes, but you can have as many active sessions as you need instead of just two.
Incognito/InPrivate/whet-ever-other-browsers-call-the-feature tabs/windows share the same session so that gives you at most two active sessions: normal and incognito.
The "new session" option in IE can have many more. For a lot of workflows two is enough, but sometimes I want something like "a couple of distinct base users, a manager, and an admin" for testing more complex user workflows.
I don't know how edge does incognito but in other browsers, incognito kills the tab history, so if you accidentally close a tab you can't trivially restore it with ctrl+shift+t or whatever.
That's one of my use cases too. It works pretty well when you're actively using multiple accounts. Amazon doesn't preserve the session very long, so I find that most of the time I open one of my AWS containers they're logged out.
That would be nice. I'd also like the to be able to automatically revert to default container when leaving a site (like the FB container plugin does), to view/manage cookies by container, and to specify more than one container that I like to open sites in so it doesn't bug me about using my default Google container when I open gmail in my work container.
They're also great for development. I have different containers for each user I use while working on logged-in flows. I can just go from tab to tab to test different user experiences or switch between users in a multi-user interaction.