There are reasons to make games.
That one reason. And it's a big one and important one. It's not the only one.
Easing up on exclusivity restrictions does concede some competitive aspects. Sometimes, things that aren't good traditional business strategies are that way because they are too pro-consumer. However, that doesn't mean that pro-consumer goodwill won't have other, indirect positive externalities.
I am not convinced that being more pro-consumer is the pathway to product death. If Product X dies on the sole reason that it eliminated its anti-consumer tactics, then I'd say that was a shitty product if that's the only reason why it was kept alive.
In other words, if Playstation dies just because they offer exclusives on other platforms (which I doubt, but we'll assume this premise is true) then it didn't have any other positive qualities to its name to justify its existence. The argument you're making makes it sound like the Playstation 4 and 5 aren't fantastic systems on their own merits, regardless of exclusives, and that exclusives are the only thing that's keeping PS from the abyss.
Apples to oranges comparison
A little more relevant comparison. You don't complain, but others do. Again, I can see why they want to keep things exclusive, but no matter how you slice it, it's still enforcing artificial scarcity. For them, it's great. For consumers, not so great.
I don't know where you're getting that part from. I never said that. I don't even agree with any of that.