I thought you'd rephrased the question to "Are you a man or a mouse? Answer the chap."
Some people must admire Joe's tactic of insisting on someone answering a question put to them.
Do they not understand that some realise that it would take a great deal of research, checking and rechecking to make a worthwhile contribution to the in-out discussion.
Obviously those who are content to throw in opinions based on snippets of disinformation that they've heard down the pub, or read in the DM, don't consider the implications of repeating throw away comments.
I suppose, also, that some posters simply prefer to debunk other's comments. So maybe their strategy is: "I don't need to win the debate, I simply need to ridicule the other sides' comments, and the debate will win itself."