Neoclassical economics can't be correct, the obvious problem is the lack of liquidity costs/taxes as a way to balance out liquidity benefits. The system breaks down if you do the right thing, so you must do the wrong thing all the time.

Taleb is in a poor position to be making fun of others' predictions.

You're being far too charitable here - the idea that Krugman has a history of being wrong has nothing to do with anyone trying to evaluate his track record in an objective manner, but everything to do with those who disagree with his political viewpoints trying to take him down a notch, especially to counter his stellar academic career. This is of course silly - Krugman is obviously highly knowledgeable about economics and his understanding of and ability to explain sophisticated economic phenomena are rivaled by few, but the nature of economy is such that anyone that makes lots of predictions publicly is going to have a long track record of being wrong.