Again, it's not about links or about comments. It's about the focus of the content. My friend, I have been shitposting on the Internet quite likely longer than you've been alive, so no, I'm not ignoring the content. And I was on Facebook for the best part of a decade so no, no shame there either.
But Usenet isn't social media. Forums aren't social media. Comment boxes aren't social media. The term came about when people started friending and following and tagging each other and generally caring who the other person is - without which all of these previous examoles are just more chatrooms and forums. If Social Media is literally just communicating in any way on the Internet, then the term is useless.