If HN was anonymous, then we couldn't see that two posts were made by the same account or not. But HN has pseudonyms with (unlimited?) pseudonyms per person, and Bitcoin is a bit like that, except that it's commonplace to have many pseudonyms (wallet).
HN is also similar to a blockchain in another regard - You can't really delete your account and its content, which really annoys me to be honest. I like to purge online accounts from time to time, but that's not possible with HN.
