I think this is really common sense. Sometimes we forget that even though we are in our homes and typing on our computers/phones, there is an actual human being on the receiving end of our messages therefore human socialisation rules still apply. I always encourage my friends to find posts that they like, read through it and then make a meaningful comment. If you get noticed, that’s awesome, it you don’t that’s fine too. The reasons for comments in my opinion are either to appreciate the writer’s work or to add your own thoughts and feedback.