it was about text chat
https://wccftech.com/final-fantasy-xiv-shadowbringers-interview-microsoft-holding-up-crossplay/
"I have explained this before, but we are prepared to do crossplay at any time. There are two regulations for Microsoft which stand in the way of making cross-play feasible. Simply speaking, an FPS-style game has no issues with those two regulations. If we had made an FPS game then we would already have crossplay."
"players with different platforms cannot chat with each other in-game."
"you cannot make a community with plays on a different platform. You can't form a guild, you can't enter into a link shell, and no free company."
all of this is complete nonsense as other games do this and did this when this interview released. and new ones have come out since that can do this.
Apex Legends for example has clubs you can join cross platform... it also has Text Chat now.
and back then I saw people bring up games that were already out at the time but I can't really remember which ones