The question is why steps of this kind were not taken, quite apart from the failure to use monetary policy (naturally as a possible second-best instrument). In the same way, it is legitimate to wonder whether confidence in the ability of financial markets to regulate themselves was not excessive.
What role was played, in particular, by the waiving of stricter supervision in many sectors of financial intermediation? This, even disregarding the strength of lobbies and instances of excessive proximity between the supervisors and the supervised.