All of the individual points that the paper makes are valid, but the primary thrust of the paper is the argument that the crisis was caused by risky behaviour, and if the players had been more aware of the tail risks then they would have been more cautious. In the events of 2008, this was exactly what happened, people became aware of the tail risks and became more cautious, and this caution created the crisis which turned into the panic which turned into the Great Recession. Would a realistic knowledge of the tail risks have changed some behaviour, and thus avoided the great recession? It doesn't really matter when the breaks are applied the result is still going to be recession.

The cause of the bubble and then the panic was compound interest. Compound interest is an exponential growth curve and it tends to infinity. Because it is exponential it is fundamentally unsustainable and will hit a natural limit and crash. Capitalism is a boom and bust system.