1. Define “so hard”. It is definitely harder to identify someone by having to trawl through all their posts and infer behaviours than simply clicking a button which gives you access to their legal ID, full name, marriage status, parents names, home address, bank account number, phone number, and so forth. Security and privacy aren’t binaries, but spectrums: each wall you put up is a new opportunity for an adversary to give up.

2. Maybe I don’t understand the question, but I don’t see how that’s relevant or true. Social media is routinely used as evidence in court.

https://www.forbes.com/sites/andrewarnold/2018/12/30/heres-h...

https://www.nbcnews.com/id/wbna25738225

>that is, do pseudonyms actually work?

If pseudonyms didn't work, no one would be proposing the policy that he proposes. And nearly everyone seems to propose it or some variation of it.