You are implying that everyone who posts on the internet may be attention seeking, which I suppose is true to an extent, as if you did not want people to see and reply to your posts, what would be the point?
To be honest, whilst that might be the societal consensus (online or elsewhere) a lot of people use their social media or online platforms as a form of diary. Where they follow/friend/add no one but they post their thoughts purely for self reference and reflection, with no interference, social media sludge nor seeking any form of intended attention.