That said, the euro area is a much larger economy than Denmark or Switzerland, so the situations there are only comparable to a limited extent. Your monetary policy works through the entire financial system. How important is it in this context for the banks to make decent profits? It can be important at least.
This is why we adopted “tiering”, or allowances up to which banks can deposit excess liquidity with the ECB at 0% interest. A monetary policy problem would arise 3/6  BIS central bankers' speeches  if the banks became reluctant to grant loans due to excessively weak earnings. But we haven’t observed that yet.