> Do you really believe the correct solution for these problems is to essentially make every financial startup a DBA of HUGE_BANK_X?

AFAIK Bancorp is not particularly huge by contemporary standards. But I see only three alternatives to being an agent of a bank:

1. Be a money transferor

2. Be a bank yourself

3. Get the law changed

None of these is very easy to do. Being an agent of a bank could be the path of least resistance.