Alright, let's use an actual definition: https://en.wiktionary.org/wiki/social_media says,

> (uncountable) Applications or websites allowing users to share content and communicate with one another via the Internet.

and HN:

[x] is a website

[x] allowing users to share content

[x] allowing users communicate

[x] via the internet

Perhaps you should invent a new term for whatever you're talking about? Depending on what you want, I might suggest "algorithmic feeds" (actually that appears to be an extant term, but it might be what you want), or "multimedia social media" (to exclude pure-text sites like this).