Yeah, I too think that is the case. And I too am using 2.81. After researching this issue a bit more, I think the only option currently is to use some addon, can’t remember its name, but there is a thread here in BA for it… Anyway - using similar approach as he, it would at least be doable on Windows, but I have no idea how to work with DLLs.
Anyway, the whole no floating windows is bit strange as any modern software has floating windows.
For example having floating outliner similar to Maya would be really nice. I already made a simple script that creates new window with narrow layout for outliner, but as soon as you click the main window it gets hidden.
Anyway, no popup windows seems to be some sort of old design choice - but it is easy to see it is not followed anymore. Drivers opens in its own popup window, and suffers similarly from not being able to stay on top. Also, Blender already has several popups for 3D viewport settings etc (which too could use more UX work), so why not add support for permanent floaters that stay on top of main window.