Call of Duty IW and MWR bought on the Windows Store can only play with other Windows Store users

Call of Duty Infinite Warfare and Modern Warfare Remastered have both launch today on Xbox One, PlayStation 4, and PC (Windows 10 & Steam). -Acitivision is the biggest 3rd party publisher supporting their game on Windows 10, but there’s no cross-play with Steam or Xbox Play Anywhere.
That’s a problem since the Windows 10 player base for Call of Duty will most likely be smaller than the Steam community. You would have thought that they’d have cross play with Steam since they are both PC.
Here is a photo confirming it as well:
Let’s not forget that Acitivision made fans angry of the fact that you had to pay at least $80.00 to get a hold of Modern Warfare Remastered and hopefully they sell it separate soon. Knowing Activision as of late they may never do that, we’ll see.