All major consumer desktop operating systems still have user accounts - you don't need a corporate system to do it.

You'll probably find that you can permanently log both users in at the same time, and then switching between them is just a shortcut and takes a fraction of a second, so it needn't be a burden. You may find it's even faster than changing the user in Firefox.

That's why it's great to do these things at the OS level - it can be done efficiently once for every app and not reimplemented lots of times badly like in Firefox.