Not sure I agree with this. They could have easily asked SEGA/RGG to make the whole Yakuza series exclusive, but instead I think they either asked for the games first or perhaps RGG Studio simply develop first for PS4 themselves. Either way, the games are starting to appear on Xbox and other platforms now, although I believe Playstation is really the only place where as of next month when the Yakuza 5 remaster comes out you’ll be able to play the whole chronological series - as well as spin-offs like Judgment, which is an excellent game.
I suppose it depends on what you’re into. I like adventure third-person games like Uncharted, Shenmue, and Japan-centric games like Yakuza. But when I talk to my friends who are Xbox gamers, I’ve noticed they tend to talk about first-person shooters and racing games, neither of which are my preference.