Google+ query

I'm nominally on Google+, in that I have a profile there, and I think I posted once or twice right after setting up the profile, months ago. I understand people I know already adding me there, despite my lack of posting. What I don't understand is why people who I have no connection to are adding me. I'm not posting, nor am I commenting, so it's not my scintillating conversation or ideas. Anyone have an explanation?