I know more about the US economy, so ill use it as the example. A bunch of risky mortgages were sold to very risky people. In the short run, huge profits were made. Industries then invested in supporting the expansion of selling homes. Places like home depot expanded to meet the desires of all the new home owners. People also used their houses as credit to purchase other things. All the things that were being purchases because of the short term wealth generation all stopped when it collapsed. Then, the industries that were built around that short term boom also collapsed, taking more down with them. The economy had to shift its focus from the unproductive risky loans business, to other more productive things. More homes were being built than could be sold, so it would eventually stop. All the industries built around it would then have to shrink to cope with the lack of demand. Boosting agg demand wont do much to help, if the money goes back into the flawed system. This is part of the reason banks did not loan out the money they were getting. Why risk a loan, when you can keep the money from the Fed, and get paid for holding their money, while the Fed gets to keep the risky assets.
I'd say this is anywhere from an oversimplification to just pretty much inaccurate. For one, there's nothing "unproductive" about high-risk loans. I'm not sure what this really refers to; the sub-prime mortgage market is alive and (somewhat) well, and those are certainly higher risk mortgages. Bubbles are inherently incoherent, hysterical and a little bit insane frankly, but that has nothing to do with Keynesian or Austrian given that both schools of thought would agree that industries that have no long-term viability shouldn't be created. There's no evidence the government created it, though. Of course, sub-prime itself was a by-stander as a primary cause for the 2008 crisis in comparison to the 1) conventional lenders abandoning federal underwriting standards between 2004-2007, essentially leading to an inability to properly assess risk levels in various tranches of collateralized securities (CMO/CDO's, etc.) and 2) the banks/institutions' insane belief that housing prices would continue to rise, and literally having little or no way to handle a scenario where prices collapse other than with CDS' that, unbeknownst to everyone else,
everyone was using to hedge their bets.
There are 2 types of reserves. There are mandated reserves by the Fed, and excess reserves. Excess reserves did not used to collect interest pre 2008, so banks loaned out the excess reserves because they wanted to make money off of their money.
http://realfreeradical.com/2014/01/04/banks-can-lend-out-excess-reserves/
So yes, the banks can convert excess reserves into capital to loan out
Banks did and still do not have incentive to earn interest on reserves through the Fed discount windows, the interest rates were and are pretty much absolutely rock bottom (though with a marked rise in the last couple weeks). Frankly I'm not sure what you're referring to, as I believe that article doesn't say what you think it does. The reason for banks holding onto their TARP funds and/or other funds borrowed from the Fed through the discount window is pretty simple; regulatory uncertainty (Dodd-Frank) and economic uncertainty (recession starting in 08) about risk and investment opportunities, with not enough potential yield to risk those reserves. The reserve requirements are also, of course, higher, as they certainly should be if we care about systemic stability (we all do whether we know it or not).
So first, Austrian's use mathematical models, they just to go as far as others do. Many believe they can quantify risk, and still do post 2008. Austrian's tend to look at models being mainly apart of the micro, and very little part of the macro.
2nd. Paying on reserves was explicitly intended to stop rampant inflation. They stated as much. Paying on reserves causes banks not to lend out the money as much, so the real money supply did not increase. Its a very important factor. As I stated before, banks are covering their losses with the interest right now. Eventually, they will start lending out their reserves instead of holding them, because the interest earned from a loan will be greater.
None of this is true; there is no evidence of 1) banks actively looking at the rates their earns on Fed-borrowed loans and deciding that's better than the higher yield they would achieve elsewhere in the real world (be it 30-year loans at 4%, take-out loans, bridge and warehouse loans, etc.). There is literally no evidence of these institutions sitting on cash
because of Fed yield on their loans. The fact they may earn some yield is just the way it is, nothing more. Doesn't change the calculus at all.
Also, Austrians have almost certainly gotten everything wrong, cause it's hard to argue with 6 years of data that would literally have to do a 180 in the next 6 years for them to be anywhere near correct with regards to inflation, commodities and U.S. equities. I can pull up all sorts of false predictions by the Austrian's patron saint, Peter Schiff, since 2008.