True, you will only get a select few who'll respond to these games. Might have a couple of reasons, one of the main reasons being (in my opinion) that not many members visit this part of the forum, even the easier spot the ball games do not draw that many participants. Ofcourse if they expressed an earlier interest it is strange that they do not follow up on it.
But I think more people then you realise have taken part in this quiz. But like me, they did not send in their answers because they don't know enough about Juve's history to complete them. I did not send in my answers cause I still lacked 5 names and therefor had no chance in winning. Should that be the case, cause in truth I don't know the real reason why there are so few who reply and this is all just my opinion on the matter, then everyone who participated(doesn't matter how many answers they got) should atleast let you know that they took part in your quiz.
Because I definitly can understand your reaction, even if you like making things like this, if you get very little responce, you'll get the feeling of "why bother?"