I'm willing to concede slightly on the XBONE vs PS4 issue, maybe they REALLY don't want their users fraternising with "the enemy".

But not letting them play with people on Windows PC's as well? That seems a little odd to say the least. Apparently Yoshi offered a XBox+PC server compromise but they wouldn't take that either and that really seems like they're being stubborn just for the sake of it and hurting themselves and their player base for bonus points.