Well perhaps it doesn't happen to you so you've never had to. Perhaps you are not a curious person.
When I opened my dashboard one morning last week I noticed that instead of 129 followers I only had 128.
Perhaps it was because he or she took umbridge at a perceived criticism of a couple of Royals. Perhaps it was because the person was fed up of my blog. Perhaps he or she is like many, perhaps even the majority, of my 'followers' who don't actually follow at all any more but did at some time. Perhaps the person was one of those who followed me in the hope that I'd then follow their blog and perhaps I didn't. Perhaps the person has gone to Google+ or is a Facebook Follower.
Life's full of perhapses.