Earlier quoted context omitted.
Why not? Minimising these impacts it's about finances, not economics. I.E Economics is about predicting these things (which they absolutely didn't), finances is about putting mechanisms in place so that if they happen they will be minimised.
Economics is not about predicting, it's about understanding things. It's basically impossible to do the former at scale for time periods over 6 months, we're slowly getting better at the latter. One big reason economic forecasting is so hard is that agents in the system you are forecasting are taking your present period forecast into account when acting in future periods.
Meh, that's not terribly convincing, as far as excuses go. For GDP predictions, for example, there are many competing institutions publishing forecasts for any number of countries, sectors, etc. It'd be impossible to take them all into account, especially when they don't agree.
I'm also not sure if "taking it into account" wouldn't actually lead to the opposite: self-fulfilment of those prophesies. After all, the prevalent reaction to an expectation of high growth would be to invest, thus creating that growth.