No, you didn't read the title wrong. How can an Xbox service interfere with sales on the Playstation 4? Well, that's exactly what is being speculated in the industry, because one of the biggest advantages of Microsoft's service is the advertising that games get for coming into their services.
Something similar has already happened in the game Descenders and Oxenfree, both of which were acclaimed for sales after joining the Xbox Game Pass according to their own developers. Also, even on Steam Descenders sold more after joining Microsoft's “Netflix of Games”. The highlight here is the marketing issue, as being included and supported by a financial giant like Microsoft, it stands to reason that the chances of success increase.
78% of The Outer Worlds physical copies were sold on PlayStation 4 in the UK, perhaps demonstrating the impact of Xbox Games Pass on retail releases. We know that on Sony's PS4, the Xbox Game Pass is not available, so Xbox One users have more options to play and don't necessarily have to buy the game at the first moment.
Remember that, although it was published by Take Two's Private Division, developer Obsidian now belongs to Microsoft, so its inclusion in the Xbox Game Pass as early as its release makes sense.
It will be interesting to see how things change with the included digital sales; The Xbox maker has argued that including "free" games as part of its Xbox Game Pass initiative leads to increased software sales, but it is a theory that has yet to be proven on a larger scale.
I'm a lawyer, journalist and fan of the Windows platform for about 10 years. I cover events and I am daily aware of Microsoft's world of consumer products.
I respond as executive editor of Windows Club.