Sony fucked 'em over.
I wasn't aware of this eventuality where a Playstation account will be required. Me and the group of friends I played Helldivers 2 with weren't aware of this either, it's listed on a side bar in the Steam page.
The Helldivers 2 devs should've done a better job informing the players of this requirement at game's launch, just in case Sony would try forcing them to link their accounts.
Adding salt to the injury, in some countries (former Eastern Bloc, Middle East, Latin America) you can't make a Playstation account so...
View attachment 5962354
...Sony sucks and fucked 'em over, but the devs could've done a much better job at dropping the bomb on the community.