Hey @DonF – my view on this topic: Equivalent of Multi-Account Containers or Temporary Containers Extension (FF) - #13 by JimB1
Especially if you use Ctrl+Shift+M to switch profiles (when needed), you get get pretty close to desired state. And in fact there are some benefits to using separate profiles instead of Containers, as mentioned in my post.
I’m with you, I’d love having the feature available, but after getting used to the new “arrangement” it doesn’t really bother me anymore.