You’re mixing stuff up, the direct connect for multiplayer where you put the IP has nothing to do with authentication that he’s talking about. Whenever you open up a multiplayer game it will authenticate yourself with PSN using the account you have on the playstation, then if your authentication succeeded it will authenticate with the game service-servers which will reply with stuff like your progression in the game, whether someone has sent you a message or a friend request, etc. Modern games are a platform in and of themselves, essentially they have an entire Discord on steroids internally which you’re using before, during and after playing online matches. If the PSN is down you can’t authenticate with those servers… I mean, they could allow you to login using username and password, but that’s: 1 not needed since the PSN is almost never down and 2 probably against some TOS from Sony for you to release games on their platform. So if the PSN is down you would not be able to get into the main screen for multiplayer anyways, so there’s no place where you could input the IP for the game-server you want to connect to.

I’m not defending the system, but it is what it is, games have organically evolved to have all of these social features which people do use and like, it makes sense that Sony won’t allow you to go over them and authenticate directly with the game specific service-servers and it makes sense that if you’re relying on all of that for login you also rely on it for matchmaking (which is where the IP would come in place). Could it be better? Sure, but there’s no incentive for it to be, PSN is rarely down and games (at least large ones) take forever to be sunset, and by that time there are almost no people playing them anyways.