The thing is that it was enforced right at the beginning. There was a period where you couldn't play without a PSN account, before they made it optional while Sony rolled out more infrastructure to handle the player numbers.

That's what I heard as well. I was a bit dumbfounded when I read that it suddenly became mandatory.

I think Arrowhead screwed up because they didn't know that PSN accounts aren't available everywhere and so were selling the game in places that couldn't play it unknowingly.

I think this is the most plausible reasoning. It's what I'm thinking as well, and also what seems to appear through the CM. In which case it is a screwup on their end. Though in 2024 I do get you'd expect people to be able make an account anywhere in the world for a company like Sony.

Steam is usually pretty good about refunds and has apparently already pulled the game from the store in places where you can't make a PSN account, so I imagine they're planning to refund the game. This looks like the kind of thing that could be class-action lawsuit worthy.

If they did that's good on them, but not wholly their responsibility. It is a good move to prevent new purchases they'd have to refund anyway ( or until there is clarity on what will happen in those regions ). I would kind of expect the publisher to do this once they figured out this was possible though :/