Simple, your phone is online, your desktop is online, and that's how you "RDP" your phone from your desktop, with no sim in your desktop.
Even if your phone is offline, you could still work with the content of your phone depending on how you set up the sync between the two, presumably similar to how you work with offline OneDrive.
'Find My Phone' may still work if your phone is switched off, depending on how you configure things.
etc.
All of the above is well within WSA potential, it is really just old technologies adapted to the WSA platform.
Although there may be true innovation also, e.g. plug a sim in a USB slot of your desktop and do even more with true cloning.
Of course, it takes a little army of code monkeys to make it all happen
Edit: I am well aware that phone cloning is fraught with legal issues, so it may take a little army of legal monkeys too