The MSDN documentation for the classes [1] clearly states the supported platforms. Admittedly the restriction to store apps is missing on the page for the namespace [2].
Minimum supported client Windows 8.1 [Windows Store apps only]
Minimum supported server Windows Server 2012 R2 [Windows Store apps only]
Minimum supported phone Windows Phone 8
Crazy that it's limited to 8.1, and not even working on 8.0.
I really wonder if there is a valid technical reason, or they just use it to push upgrades.