Well you sign in into those other services like email or steam because you need an account to use those services.
But a single player game released on steam does not need it. Steam provides its own DRM that publishers/developers can use if that’s what they want to achieve with an account.
Case in point the mod this post is about, the game doesn’t need an account yet Sony is trying to force it.
There are a lot of things you can survive without :)) They are still nice to have though.
But I understand the privacy concerns, I struggle with the tradeoffs myself. But to me it’s worth it it this case since the database is supposed to be encrypted with a passphrase and stored locally, not sent over a network.
Other examples would include searching through history to check if you’ve talked to someone about something. Or check their answer. Unless you are someone with perfect memory I would think these are common situations.