I used to use Ion3 on a tiny Fujitsu Lifebook P1510D to divide the screen into quadrants containing things like a terminal (mostly used for IRC), Pidgin, a browser, and whatever videos I might be watching.
I guess it makes sense if you have a bunch of apps you're predominantly reading from instead of interacting with but in my experience those are predominantly terminal UIs anyways.
If I'm on a machine without a tiling wm I generally using everything maximized and alt-tab like you say. But that's still usually an extra click after opening an application.
I also love tmux, but I have a coworker that doesn't see the point.
So, having options is nice. I want to be able to work the way I want. I also want you and my coworker to be able to work your way.
I've never really given it a fair shot.
You must be a C++ programmer [1].
[1] https://stackoverflow.com/questions/25224958/dereference-a-p...