Sharing also adds to something in mk's magic mix causing dots to appear around your name or perhaps around the sharee's name. When you complete a full circle, you have more privileges. If you comment on it and want more people to notice your comment, perhaps people might add a share. I imagine sharing is someowhat idiosyncratic. Also worthy of note is that people do not just read what is in their feeds. They look for interesting comments in chatter and badges and unread, unshared one-starred bits in "global." Anyway, no rush. Hubski never sleeps..Actually one more question, what usually makes you decide to share a post? Is it that you agreed with it, thought it was interesting, thought it added to the conversation, all of the above?
Sometimes posts are shared ironically, sometimes even badged ironically.