Sony sold H1Z1-developer, Sony Online Entertainment (now Daybreak Games), long before PUBG was even a thing (February 2015 vs March 2017).

It has nothing to do with H1Z1. Microsoft brought PUBG to XB1 with 1 year timed exclusivity.

 I guess you forget when Bluehole was forced to admit that “cosmetic” items like ghillie suit did actually give players who had it an unfair advantage, and were forced to classify it as a pay to win item. 

Took them long enough.

I knew about the exclusivity but I figured even without that they wouldn't. Thought it might have been part of the reason PUBG agreed to it. Didn't realize Sony sold the game though. 

Now that I read my post, I sound more harsh than I intended

If Sony still owned them, I could imagine that they'd want H1Z1 to capture a big chunk of the Battle Royale marketshare before other games arrived on PS4. And in this case, it would've made more sense for Bluehole to take the money from Microsoft and make PUBG exclusive to XB1 for a year. As it stands now, Bluehole has made it very difficult for themselves to succeed on PS4.

I could be wrong though. Time will tell.

You're right. The units seemed to operate completely independently.

PlanetSide 2 was out on PC for over 2 years before finally arriving on PS4 (with a long delay in the process iirc).