I was on another forum that moderators would identify unanswered questions that could receive a simple answer. Those moderators would then restrict the poster to answer the question on that thread. Sock puppets would get banned, and the next post allowed would be monitored by the moderators to answer the question before it was posted. Since the moderators didn't have infinite time, they would more often than not only give the poster a single chance to answer or get banned, but it was at their discretion. Bans started at 3 days and went up from there at the discretion of the moderator.
I realize we can't do this on TOL because the resources necessary are too much, but it sure made for a lot of productive discussion. I got caught not answering a question and they were happy to get an answer that explained why I found it a disadvantage in the argument to answer either way the context would allow, which included my preferred answer. The discussion was fruitful after that.
People like Arty, Jonah, Anni, Russa, Quip, and a few others would need this kind of discipline to offer anything useful.
And, were there, on TOL, a penalty of permanent expulsion for liars who, in addition to stonewalling against simple yes-or-no questions, lie by saying they've answered those questions that they clearly have never answered, then Arthur Brain, being one such shameless, hardened liar would have long since had his wholly attention-begging/trolling career on TOL terminated.