My argument with Mr Puggsly initially started because he thinks that Microsoft's main problem right now is that they should focus on expanding their studios and games portfolio and think about selling them to bigger crowd. (That's why I asked him "why don't bring them to playstation then"). I disagreed with him because IMO, the bigger problem for Microsoft is awful potential market penetration worldwide and provided an example for that. It doesn't matter how many awesome games you make, if your brand and services like GamePass (which is MS main focus right now) become irrelevant outside of US and EU West. Because you won't have the ability to sell your games and services to the huge part of the world.
There could be many reasons why GamePass ain't on PlayStation. Sony probably ain't allowing it, they also didn't allow EA Access for many years.
Selling Xbox games on PSN would also help the direct competitor and give them a lot of royalties.
And why is the GamePass irrelevant outside of the US and Western EU?
GamePass is currently available in Argentina, Australia, Austria, Belgium, Brazil, Canada, Chile, Colombia, Czech Rep, Denmark, Finland, France, Germany, Greece, Hong Kong, Hungary, India, Ireland, Israel, Italy, Mexico, Netherlands, New Zealand, Norway, Poland, Portugal, Russia, Saudi Arabia, Singapore, Slovakia, South Africa, Spain, Sweden, Switzerland, Taiwan, Turkey, United Arab Emirates, UK, US.
The underlined countries aren't US or Western Europe. Russia is one of the biggest PC markets, so PC GamePass should do quite well there. India as the country with the second biggest population has a lot of potential.