Rules of Engagement?

I have been adjusting to "silent observers" of social media, particularly when we interact in person. I have had several instances of encountering someone who referenced content I had posted, but had never responded in any way I could see. The first time this happened, I stumbled upon a person who was in a Facebook running group where I post lots of pictures and comments.  As we talked, she repeatedly referenced different items I had posted, but when I asked if her profile name was different (because I didn't remember seeing any of her interactions with the content), she said, "Oh, I never say anything. I just watch." It makes sense to me that there are people who just watch others' conversations online, but I find it interesting that they later choose to "reveal" themselves and their viewing habits.

As one who really likes to keep the "social" in social media, I engage with other users by commenting, replying to tweets, etc. For me, the interaction around content is of greater value than the content itself. I learn the most when I understand others' diverse interpretations and experiences of the same information I have received.