The point is to dedicate maximum screen real estate to the primary thing you’re working on.

I tile within one monitor when I legitimately want to see things side by side, but I certainly don’t want firefox permanently taking up screen space when I really only need to occasionally look at it. Usually it’s on a separate monitor in the same workspace, or in a dedicated workspace.

Maybe there’s some way I could manipulate stacks and zooms to achieve that within one workspace, but I’ve always found it easier to just have firefox on a separate workspace I can easily quickly swap to and from when needed.

If you are trying to maximize screen real estate to the thing you are working on, why not just use a regular floating window manager will all the apps full screen? I don't see how that isn't equivalent. You can even use multiple workspaces with them too.