I'd argue that generally speaking, the problematic social media tend to be ad-supported websites that focus on user-generated content.
so Facebook, Instagram, YouTube and Reddit are all social-media, because all are ad-supported, and all are focused on user-generated content. HN is focused on user-generated content, but not ad-supported (okay, technically HN is 'advertising for YC', but in practice, the site isn't optimized to get you doom-scrolling so you click on more ads), and a website with a comment section, if it's like a blog or something where the majority of the content is generated by the website owner, isn't focused on user-generated content.
The combination of user-generated content + advertising, however, seems to create websites that will try to get their users addicted to the site, which can harm the lives of their users.
so Facebook, Instagram, YouTube and Reddit are all social-media, because all are ad-supported, and all are focused on user-generated content. HN is focused on user-generated content, but not ad-supported (okay, technically HN is 'advertising for YC', but in practice, the site isn't optimized to get you doom-scrolling so you click on more ads), and a website with a comment section, if it's like a blog or something where the majority of the content is generated by the website owner, isn't focused on user-generated content.
The combination of user-generated content + advertising, however, seems to create websites that will try to get their users addicted to the site, which can harm the lives of their users.