Steam

The issue isn't so much the PSN requirement, its the PSN requirement after 4 months of building up your character and buying in game currency. If this had been a requirement on day 1, people would grumble, but it wouldn't cause outrage. It's a rug pull, a subversion of expectations, the antithesis of what AH was supposed to be doing.

it feels like a betrayal.

Not to mention the required PSN account, means you now have to accept the PSN terms and conditions and if you don't you lose 4 months of character work and any in game currency you bought..

PLUS PSN is only available for 69 countries, about 33% of all countries in the world. That means many helldivers simply cannot make a PSN account at all, and are facing the prospect of losing everything (unless they lie to make a PSN account using a VPN, which is banned by the PSN terms of service, so a real catch-22).

.... so.... a betrayal

The PSN account, which is free, was required but turned off during launch. It's been working fine. Now if you don't link your PSN to steam you can't play after the end of this month. You lose a PC game on steam because you don't have a PlayStation Network account.

It's totally unnecessary and Sony has a shit cyber security track record.

Sony has shot the game developer in the face with this.

The tl;dr seems to be:

After such and such date (end of the month I think? Sometime soon either way) you will be required to sign in with a PSN account in order to play. Some say this was not advertised when the game launched, some say it was (I believe people found wayback machine captures that say it was but I may be wrong. Some people don't want this, some countries aren't allowed to sign up for PSN accounts outright (and if they have Helldivers 2 they would then be losing access technically).

Sony offered up the usual explanation of security and whatnot, which most aren't accepting that as Valve/VAC do the job of security, leading most to assume it's a way for Sony to gather more info and data from customers which they can then sell or otherwise market somehow.

Overall souring people on the whole situation of a bit of a bait-and-switch.