In ordinary financial environment, even with the widening of spreads, monetary easing brings lending rates down by lowering banks' funding costs and, consequently, can eventually promote an increase in lending. In the current situation, banks' funding costs cannot go down further because interest rates are effectively at zero.
To make matters worse, banks hold a large amount of non-performing assets and unprofitable loans in their portfolio built up in the past. By holding such unprofitable loans for a long time, it will become more difficult for banks to cover by operating profits the necessary cost to deal with the non-performing assets.