This approach was dropped in 1970 as it proved 1/5  BIS central bankers' speeches  difficult to precisely determine the adequate quantum of bank capital in the face of the growing complexity of the system.
The long period of financial repression, that is, direct control on bank lending to the private sector and force-feeding banks with government debt instruments had made the core business of commercial banks safe between the mid-1930s and the early 1970s. Central banks’ function of maintaining financial stability by way of regulation and supervision had atrophied.