Microsofts music, Microsoft's GPS, Microsoft's navigation, Microsoft's phone software -- and only Microsoft's -- gets to do this. The issue is what third-party software is allowed to do. You yourself said all third-party software gets paused. The iPhone allows certain necessary functions to continue.
Again, you show you don’t understand. Twitter - the Twitter-created program - multitasks in the background. Microsoft will check to make sure it’s stable and not a CPU hog, then allow that program to multitask.
Flat out - you’re wrong. Quit spreading FUD.