I think those things are a bit more black and white.
How do you define social media? Is HN social media? You engage with others through comments, posts are ranked and it has voting elements as well as your profile has a gamified score for upvotes. Is a Disqus comment on any website social media if that's how we broadly define social media? Where do we draw the line?
You could make a case that leaving reviews on a site are a form of social media too. You can post something there and feel like you need to check back in hopes someone leaves a like or replies. If it were a wearable item you might take a picture of yourself and now hope people engage with it.