Recently, Spotify Connect enabled controlling the desktop app with a mobile device, but this is not complete!
Allow the controlling of Spotify Connect devices with the Destop App. For example I can control a mobile device from my PC, or I can control the PlayStation app from my PC.
Right now I run a virtual machine with a virtual tablet to run the Spotify Mobile app to use Spotify Connect to control devices from my PC, when I should be able to use the desktop app in the first place.
Closing this idea topic. As mentioned Spotify Connect (for desktop) is a Premium only feature.