The biggest reason is likely due to leadership change.
No, this is a first party games thing, so Studio Business unit thing. So a Hermen decision. And well, Hermen has been in charge of first party games since many years ago. Same as Nishino, he has been in charge of platform/PSN/etc many years ago.
It was soon after that they removed mention of PC ports from their financials, and likely began an investigation on what to do.
No. They kept talking about then when it was a novelty, during a couple years. But when expanded MLB to Xbox and acquired Bungie (so had Destiny 2 on Xbox too) they switched to talk about off-PS first party revenue instead, and kept reporting it every quarter in their fiscal report as "other software".
I do however predict they will pull their own studios away from GaaS moving forward and work with second parties (like Arrowhead) to produce them, as it provides less risk for Sony's own studios.
Do you really think they will shut down Polyphony Digital and Gran Turismo, San Diego and MLB, Bungie and Destiny+Marathon, Team LFG and whatever they are doing? This would be really nonsensical and suicidal.
Sony's DNA has always been storytelling, that's what they're beloved for and everyone knows it, even Sony.
Storytelling has been important for them, but Sony always made games of many genres (see MLB or GT), and in recent years they are experimenting with expanding their first party games to more genres they didn't dominate at least in recent years, particularly in different shooter types, in many cases trying to introduce a strong narrative in MP:
Coop third person shooter with Helldivers 2, looter shooter with Destiny, extraction shooter with Marathon, hero shooter with Concord, roguelike bullet hell shooter with Returnal, VR MP FPS with Firewall Ultra, hack & slash with Stellar Blade, 3D action platformer with Astro Bot, team based heist game with Fairgame$, Monster Hunter clone with Horizon Hunters Gathering, whatever was Midnight Murder Club and many more.
Sony have never been willing to release their big games on PC at launch.
They did and have been working on it did since 2017. This year they'll release Death Stranding 2 plus day one games like Marathon, Marvel Tokon or Horizon Hunters Gathering.
Most AAA nowadays cost over $250-300M, meaning for most AAA games to get profitable isn't enough to release a SP game without DLC in a single console because need to sell around 8M copies to be profitable, and while this is not an issue for the top seller IPs, for most others is almost too ambitious or unrealistic. They need extra revenue, that's why all AAA publishers have been betting more on crossgen, multiplatform, GaaS and mobile. Plus in some cases like Sony, off-gaming adaptations. To get that revenue directly or indirectly.