The trouble is that other US government interventions also eliminated a big chunk of the "anything else to do with it". In particular, most mortgages in the US are fixed rate for the entire duration of their term through government backing, which almost entirely eliminates one of the big sectors of loans that banks in other countries can use to make money on the premium from interest payments with less duration mismatch than 10-year or 30-year bonds. In most other countries, mortgages are either variable rate or only fixed rate for a relatively short period. Also, a substantial proportion of all US mortgages in existence apparently locked in their interest rates during the time period in 2020 and 2021 when they were at record lows.