This is not true, this change is a recent phenomenon, I believe it came into effect sometime around 2021-2023 (maybe earlier even). I believe it changed when OpenAI showed the value of data.

Before, there was no problem using Instagram or Twitter while not logged in. Now there is a dark pattern that forces you to create an account, or log in.

False. You used to be able to read Twitter fine without being logged in

Instagram explicitly tells you need to be logged in. Twitter/X just appears to be broken

Obviously wrong. The typical user-hostile thing isn't this dumb, you'd see a teaser that's probably vaguely sexual and get some "sign up for the full experience" prodding. Literally any 2-person startup that's a week old would do better than this at being thirsty and awful