This forum is social media.

Not by colloquial usage of the term, which is often (and in this case) limited to the subset of larger global human-content firehoses where the problems inherent to that dynamic become more dramatic, e.g. Twitter, Facebook, shorts feeds, things like Instagram and Reddit maybe, etc.

Hacker News is Reddit with tone policing and a nuclear downvote button.

The only difference is scale, and with the increasing flood of bot users and throwaway alt accounts, that's starting to matter less and less.

HN is just as much an echo chamber as any facebook group or subreddit. You are making a mistake if you think you are immune from groupthink and herd mentality by limiting your online discourse to this platform only.

Social media is where one shares ones social live; its in the name!

Whist there is often plenty of crossover (think car enthusiast forums), I'd hardly call a technical discussion site 'social media'.