Community-scale banks (aka credit unions) are a better idea for local-regional communities (aka cities and towns and agricultural regions) because their managers have to live with their clients. Take a community of 100,000 families, in an economic system where they're all collecting income and paying bills and so on. The idea behind a bank is that they hold the community's money securely while making their own money…
The model you describe is exactly why S&L happened . Small banks with highly correlated deposits holding their own loan books is a recipe for maximizing vulnerability to economic shocks. Interest rates go up and the loan book loses value; the local housing market drops and the loans get foreclosed and lose value; a major local employer goes out of business and depositors all start pulling their money out instead of r…
Economic shocks and rising interest rates aren't usually the reason that financial institutions engaging in risky or fraudulent behavior get caught, they usually just make it so the clock runs out on their scheme to roll over the losses or otherwise avoid getting caught.
The liquidity crisis of 2008 didn't cause Bernie Madoff's fund to collapse, the fact that it was a complete fraud from inception did. It just made it impossible to ignore.