The aim was to keep the credit flowing and limit the need for fire sales wherever possible. An important motivation for this first phase of quantitative easing (QE) in the US and elsewhere was addressing the market dysfunction. Indeed, for a time, the Fed characterised it as credit easing. This first phase of QE was particularly effective.
My view is that subsequent phases of QE had diminishing returns, though I acknowledge that much of the empirical evidence tends not to find that. A question worth considering about QE is: if QE was effective on the way in, then surely there must be a large degree of symmetry? Hence we should expect to see similar but opposite effects on the way out.