Sony is different from Microsoft in that they can test things out and change their plans whenever they want without any serious damage to the Playstation platform. The moment they feel porting games is harming them as a platform holder, they'll be sure to return to the old ways or add a new limit to their porting strategy. They are searching for the right balance.
Microsoft probably wouldn't return to exclusivity because it's too late and would be confusing. They think it isn't worth sacrificing dozens of millions of software sales. They're a publisher first and a platform holder 2nd. CoD on a medium sized PS install base seems to dominate Xbox + PC sales combined, so it takes courage and a hint of lunacy to mess with that. MS can literally kill the Xbox brand (and GamePass) and still be a bigger gaming entity and make more money than Playstation.
Curiously, Sony sequels on PC seem to be doing much worse than their predecessors despite building a playerbase and everyone knowing their "exclusives" are coming. I wonder how the decision makers at Sony are taking this.
As long as ported software sell a decent amount and won't hurt Playstation's hardware sales, Sony's testing might extend to Nintendo platforms beyond weak games like Lego Horizon. If it doesn't work well for them, they can pull the plug without much trouble. Porting a few games to Switch is somewhat risky, but it's a risk that makes business sense. I think Playstation is strong enough to withstand risks of this level.
Essay Pro