mr p raises a couple of separate things.
First while in isolation it may be argued that bank exposure may not correlate with state intervention, interbank transactions would have brought down the market exposed to toxic debt, largely in western banks. The price of stemming that catastrophic market failure is effectively that the market restructure that was stopped has to happen now in drips. Lenders find their asset values falling, and borrowers find they owe less. Separately the lack of [direct] demand stimulation is adding a contracting dimension to market restructure. Quantitative easing has not improved liquidity or stimulated demand, nor was it really ever going to. But it's a nice show, and the fact that it's still happening means they think we believe it works.
Secondly the return [and not new introduction] to segregating retail from investment banking is a limited gesture to contain market failure. Market failure affects everyone who has bank dealings, not just shareholders. So that's bank account holders, commercial borrowers, staff, we all take the hit. The understanding of this exposure in the East [that is the state would definitely NOT bail out an over-exposed bank] meant the exposures our banks took were refused by Eastern banks. They did not expand [or get rich] in the way we did, so now enjoy the relative abstention from the market restructure we are going through.
You could say if we can't play markets properly, we shouldn't pretend that tinkering about the edges and building a dam here and there will stop the market from levelling out as it's meant to. And level out it will. In the old days we called market restructure "defaulting", which is exactly what we now have to do in drips.
The other trouble now with stimulating demand directly [which I doubt the current team is intellectually/politically agile enough to do] is that supply may come from other countries and we'd be importing their deficits rather than just growing our economy. UK depression is one thing. The rhetoric that accompanied it has infected others [so their austerity measures have also depressed them], hence changing direction is harder to control.
Despite all the obvious unfairness of foreigners pricing us out of UK assets [a common complaint], it may be better than free fall due to having nothing worth buying. After all, if the assets fall in value, then effectively they, and not we, have taken the market adjustment.
However we got here, getting out requires skill and somehow the economic lessons from previous depressions seem ignored [so far] or beyond our current Government. When you fail, it doesn't matter if it was intent or stupidity, you just fail. A mere two years into this administration, it's a long long tunnel out.