Yeah, that’s what they’re for. Having multiple accounts separated and not interfering with each other. So you can have eg. three different tabs of Gmail open or office or whatever in the same window with different accounts logged in. Each tab with a different colour. Great for separating work stuff from personal stuff or isolating bank logins etc.

Sounds like the same thing as you’re describing in chrome (though I haven’t tried the chrome implementation)

Firefox account containers are very clean and easy for this. The tabs get colour coded based on which account is logged in and you can configure certain sites to always open in certain containers.