Hacker News is almost indistinguishable in spirit from a well-run subreddit. Reddit is not centered on user profiles and followers and yet, Reddit is included in the Australia's social media ban.

It is clear from the ruling that by including YouTube, Reddit and Facebook, they take a broad definition of what social media is, essentially anything with user interaction and Hacker News definitely fits the bill.

And if your criteria includes "social aspects like user profiles and followers", then GitHub would fit too: it has user profiles, followers / stars, and allows for discussion. It is even included in the "social media" list for ESTA and visa applications for the US. We could even include StackOverflow, I mean, it used to be common practice to build a profile, chasing a reputation score so that you could show off to recruiters.