MS solely held it back at start of this gen.
http://m.ign.com/articles/2013/07/09/why-final-fantasy-xiv-isnt-coming-to-xbox-360-or-xbox-one
"The game director of Final Fantasy XIV: A Realm Reborn has explained the title won't be coming to Microsoft consoles as Xbox Live policies don't support cross-play with other platforms.
In an interview with
RPGsite, Naoki Yoshida explained that while PS3, PS4 and PC players will be able to play with each other when the game launches on August 27, the fact Xbox users would require their own server turned the team off.
"The policy has not changed on Microsoft's side," he revealed. "The main reason from our side is that I don't want the community to be divided; to be split into two or more. For example, one player might be on the PC version, another might be on the PS4 version, and I'm playing the Xbox version - but we're not able to join the same game servers. That is just... I just don't like the idea. I disagree with it."
This is while Spencer was running things and was in active talks with SE and they wouldn't budge!