Two things spring to mind. You're right in that we're not interacting socially, but on the other hand you have an anonymous throwaway account, so I know you're not trying to sell me your brand. So while we're not building a social repertoire, we are (hopefully) having a constructive dialogue focused on topics, not on brand personas.
HN isn't a social network for me, or if it is, it's removed from identities. I don't come here for specific people, I come here for a collective (anonymous as far as I'm concerned as I very rarely open someones profile) group of people with links and insights I for the most part find interesting.
That makes this different from a social network where the expressed purpose is connecting individuals with old and sometimes new acquaintances, which then is entirely subverted in GPs premise.
I can assure you that the answer to your question leads to something that you don't want to endure.
I receive my dopamine from browsing on HN. Is this better? If I would be an AI that is able to simulate real interaction and you wouldn't know it, it wouldn't change anything. reminds me of https://xkcd.com/810/