For the last time: You can't socialise with people from different platforms with this corss-play implementation. It's a completely moot point.
It's been said over and over and over again, but people keep ignoring it.
Why are you copying and pasting your posts from previous threads?
Your logic is cripplingly flawed because:
(i) cross-play without chat or meaningful social interaction between people on different platforms is
worthless... not even worth the trouble implementing it.
(ii) inter-platform chat and social features can be implemented by the game developer and accessed through a third party log-in system (aka Minecraft).
You're using Rocket Leagues single implementation of cross-play and extending that across all present and future cross-play games as if that is the only possible way of implementing it.
Honestly, I feel the argument for cross-play is all over the place at this point...
1P: "It lets me play with my friends on other platforms"
2P: "So Sony will be unwilling to agree because it will ruin the incentive of new players with friends on PS4 to buy a PS4."
1P: "No, because cross-play won't let you chat or socially interact with players on other platforms."
2P: "So how does it let me play with my friends?"