It’s an extremely long-winded way of saying that lending moving from bank lending to bond/money markets. The fact that depositors did not take much direct credit risk is a red herring.
I don’t see the financial logic, but yes, the banking sector moved from being lenders to underwriters of securities.
Bond and money markets are decentralised: instead of a ...
Someone could write a book about this question which still wouldn't cover all considerations. However from a high-level perspective, I would say that TR handles a lot of cross-functionialities with a main focus on risk mitigation, like especially
interest rate risk
and most of the times TR also covers the pricing ...