Because it gives them extra hundreds of millions of revenue/profit with little effort/budget required, and help them reach many millions of players who never would buy a console.
It's a catch-22 and almost self-defeating ideology though, not to mention wrong on some level. A lot of today's PC gamers WERE console players in the 360/PS3 and PS4/XBO gens. But because of various reasons on those respective platform holders alongside Steam growth, they moved from console and went to PC.
In other words, the platform holders could've done more to retain those players. Sony could be doing more today; porting at least non-GaaS titles to PC does not help them in that regard and it also shifts potential customers out of their direct ecosystem (PS console & storefront & subscription service & peripherals). At least with the trend they have been increasingly shifting towards the past couple of years.
Specially in strategical countries where they want to grow like Asia (particularly outside Japan) and Latin America.
People in these countries, the Middle East, Africa, etc. have always had means of access to some extent to prior consoles. Let's not pretend consoles have been complete non-factors here, particularly when it comes to Sony. In places where there were laws preventing legal console sales for a while, like China, those laws have since been removed.
If you don't condition customers to buy a certain way and at a certain place for a period of time, then of course you won't convince them to buy in where you retain the most control as the product's owner. But people in these various other countries are not inherently against getting a console for gaming needs, even if the console is supplementary.
They see it as a great opportunity to highly grow their business with very little risk, and no signs to negatively affect their console business (which continues growing too). Same as expending to make more MP & GaaS games, mobile gaming, adapting their gaming IPs to movies/tv shows/theme park rides/etc.
Dunno, sounds like there is some inherent notable risk if even Jim Ryan is now saying PC directly competes with PlayStation (and it does).
The console business is growing but that's partly due to inflation, partly due to increased costs in areas and now we are seeing Sony get more aggressive with pricing deals and discounts to shift units for meeting fiscal targets. How much of that is proactively planned well ahead of time vs. how much is reactive to possibly lessening demand (even if only slightly) is up for debate.
Doing more MP/GaaS titles in itself is a good thing, just depends on how fresh the game concepts are, if they're being smart leveraging legacy IP, and try not entering too many saturated genre markets in that regard. Same with the mobile games. Gaming adaptations to shows/films/theme parks etc. makes sense but again, there has to be a balance of variety and in ways that make sense. As an example, that Gravity Rush adaptation should've been at least a CG anime, IMO.