Because Google search is creepy and likes stalking your Internet activity.
I was searching for an old friend the other day and I've searched them a couple of times and now my linkedin image displays when you google search their name in the google image search results. Why would my image display in their results?
You need to create some pseudonyms for yourself if you want your online activities to be semi-anonymous. (I say "semi-anonymous" because I don't believe anything we do online is truly anonymous.)
