... and why do people call it "social media"?

I've only encountered it a few times while looking for answers on technical problems. And it looks like some kind of forum to me; I don't see the comparison to Facebook, Instagram, etc...

Meh, I don't see it as much more "social media" than a more traditional forum.
That said, I don't have an account there. :P It seems like it used to be a halfway decent -- though much less populated -- alternative/addition to this forum (though I've only ever lurked); ever since Galaxy 2 was announced, though, the sub has been flooded with talk of little else. Unless you care about the [new version of] the client, there's barely any point in visiting anymore.

I check the GOG sub-Reddit daily and now only go to GOG once or twice a week. I used to access GOG more frequently when their frontpage had easily accessible news articles, but since it changed a couple years ago I no longer like it. The GOG sub-Reddit now lets me know whenever there's an important game release or sale.

I don't even know what exactly is "social media". Why isn't this GOG forum "social media"? I am discussing about different subjects here online with other people from all around the world, am I not? Even publishing photos of what I just ate or defecated?

What makes this so different from Facebook, Whatsapp or Twitter? Is it because there I can limit what I show to whom? But then, isn't that the same as email or private messages on GOG?

Bah, whippersnappers, coming up with new words for old things.

Nope - never used it.

I read it sometimes but I rarely post.

It seems too much about Galaxy 2. I'm in but rarely find anything interesting.

I do.