An individual bank has a large amount of discretion in the way it funds itself, as it can bid more aggressively for the type of funds it wants and compete them away from other banks. The banking sector as a whole, however, has much less flexibility.
For the banking sector as a whole to increase its use of deposit funding, it needs to be able to induce a shift in the structure of the financial system away from financing through capital markets to on-balance sheet funding through the banking sector.