This bit from
the article is interesting:
Just checked the website for the game and saw this:
•The ultimate multiplayer experience: Play cross-platform on Nintendo 3DS™, Wii U, iPhone, iPad, iPod touch & Android devices.
Looks like Sony rejected the invitation for Nintendo Network/PSN cross platform play, then. And only the Nintendo and iOS/Android versions support cross platform multiplayer -- PSN is strictly PS devices only.
Worth noting as far as Rocket League on Xbox One will go to supporting multiplayer with PS4 players (so far an invitation has been sent out, much like how one was for Pure Chess on Wii U). Though the publicity of this might cause Sony to change their mind - this is out in the open, whereas barely anyone knew Nintendo Network supported it.
As I mentioned earlier, it's not in Sony's interests to lessen the sales the leverage they can pull to sell PS4s to those who want to play with other PS4 owners -- and there are more of those than XBO owners.