Necessary for whom? Every single use case for assigned identity reduces to enforcement. It is not a consumer product people want, it's a tool to herd people. These companies and so-called foundations are just jockeying to become the next Hollerith.
Identity schemes don't need features or complexity as once you're subject to it, it can be a crappy yellow card or even an arm band you carry with you and present it when it is demanded. The rest is theatre.
I was going to say that identity is useful when replying to a comment on HN :) but you're right that the comment text could stand alone. The poster's identity is only needed for karma sorting and greylisting of comments.
Identity schemes don't need features or complexity as once you're subject to it, it can be a crappy yellow card or even an arm band you carry with you and present it when it is demanded. The rest is theatre.