Quote Originally Posted by era1Ne View Post
This is wrong according to the rocket league dev
Rocket League is a completely different story and genre. MS wasn't on board with cross-platform during the majority of development:

Dunhan noted that this cross-platform idea had been something they asked Microsoft about when Rocket League was set for an Xbox One release, but he stated that Microsoft did not seem to be on board with it. Only after they had neared the release date would Microsoft take the initiative to offer the title as one for their new cross-play efforts and started working towards this possibility in the game.
Which is why it wasn't turned on until a later patch on XBOne.

There is also zero mention of the actual agreement which is required between MS & Sony for cross-platform and we likely won't hear of its details publicly.

So it isn't as simple as "Sony just has to turn it on". Sony & MS both have to come to an agreement to enable it.