As for HN and marketing programs, you may notice that Hacker News is run by Y Combinator. YC has a considerable interest in owning the news platform for startups and engineers. This is not a coincidence.

Not anymore than any other service that to work asks for phone numbers or email addresses.

You might not appreciate or have a use for the service, which is tongue in cheek, but that doesn't make it "malware" or "social engineering".