P&M V - Guess Who I Am

"Guess who I am?"
Ah! I had lived long enough to know that the person asking me this question could belong only to one of three categories
1. Someone from school or college who I have not seen for lo these many decades. Having recognized me, despite my crude attempts at disguise like some additional twenty inches around the waist and a shiny pate, he expects that recognizing him should be a piece of cake for me. 2. Someone who I ran into in a jamboree like a wedding or some party some time in the past. Why I should have been memorable to him is something that only he can explain but why he has not  been memorable to me is now my task to explain to him. 3. A variant of 2 above - someone who I ran into in a party, when I was wandering around in an alcoholic daze, hardly noticing mere humans what with exotic creatures like pink elephants and flying mice having captured my total attention. He would have had a better chance of being recognized had he been a Hobbit or a Balrog. What makes it tough to explain is the fact that he is possibly one of those unfortunates who have an impaired eyesight - owing to a regrettable indulgence in those abominations called soft drinks - and are unable to see the wonders that are visible to the more fortunate.
Unfortunately, identifying the categories is as far as I have been able to get. In almost every instance I have failed miserably to identify the person concerned.
Hitherto I had confined myself to phrases that meant something different from what the dictionary would literally have them mean. In this case, however, the person who asks the question means exactly what he says. He/She does actually expect you to guess who he/she is. The problem for me is in identifying what makes people indulge in these guessing games.
If ever there was a question that was designed specifically to cause unhappiness to the person asking it, it is this question. I have heard cruel replies like, "I never knew you and do not want to" to "If I had guessed, do you not think I would have ducked out of sight in time?" Such wounding replies have been rare but, more often than not, the other person has had to indicate his inability - or guess wrongly - causing the questioner to feel hurt badly. It is a rare case where the recognition happens as expected - and the joy of such recognition is not really mind-blowing. Seems to me like this question is the sort of lottery where you buy a ticket for a million bucks in order to possibly win a humongous jackpot of one buck. So, why do some people play this game where the potential losses are huge and gains paltry? Masochism?
It is also a fact that most of these instances have left me vaguely guilty for the lapse of memory and vaguely resentful of that person as a consequence. There is this one instance, however, when I felt neither.
"Guess who I am?" came the tenor voice over the crackling static of the telephone connection.

"I do not know", which has been my invariable reply. I never really could play the 'your voice/face/whatever is very familiar and your name is on the tip of my tongue' game very well.

"What is this? We were so close till the 5th at school when you moved away" came the distressed, wounded voice.

Ye Gods! That is one time I could not have apportioned even an iota of blame to my memory. I defy even God to hear the tenor voice over a crackling telephone, discern the childish treble of thirty years ago and go on to identify the speaker. I swear, this really happened.
Now, can someone please tell me why people ask "Guess who I am?"