[safdahfslh23s]

You are missing point - the dark pattern is that medium told the user in exchange for creating an account, they could read the rest of the store. They created an account and then were told they could not read the rest of the story. The sign up flow lied to them. It's the equivalent of an e-commerce site saying "Sign up to get 50% off any order" and then when you signed up there is no discount on your order.