likes and comments aren't social?

Only on the most shallow level. Early Facebook was like meeting up with friends. Modern social media is like shouting at strangers on the street.

Not if there's no reputation. If you see someone liked your post and then you go check out their posts, or if people recognize commenters and remember things about them, then it's social. Think engaging with friends on Facebook or participating in a hobby forum. But there's nothing social about engaging with a popular Reddit post or some celebrity's Twitter feed.

I get where you and parent are coming from. It's social in the way that anti-social behavior is social.

The content is generated by users but the consumer of the content is served whatever user content drives engagement. People aren't really having conversations on these platforms.

The only places where you can really have a conversation are places where engagement is low enough that the odds off a set very high engagement comments can't shove everything else down the page.