The purpose was stated BEFORE the threads were combined.
I couldn't state the purpose in the four separate threads because the whole idea was that the posts to THOSE threads would be spontaneous. I'm sorry that that caused you some confusion.
Why would such a song challenge be dumb? It is no more than an on line extension to the Limerick party game.
It could have been fun had some over officious editor not combined the threads.
A perfectly good song challenge was completely destroyed because some editor's sticky fingers were not connected to his brain.