No he isn’t? Social media is centred on posting about yourself and following people to see what they post. This is a link aggregation site with a comments section. By the definition of “place you can go and post comments on a topic”, then Usenet is social media. Every website with a comment section is social media
The letters section of your newspaper is social media. No, the whole point and problem of social media is that people make it about themselves.
Yes. Microblogging in general. It started bad with “had toast this morning” and “look at my lunch” and somehow we got influencers out of it.