That's kind of like saying you won't use web services because you don't want a "hot potatoe" [sic] problem between your ISP and their ISP when there is an issue.
Businesses contract out services all the time. In this case, BankSimple is using some established company to store your money. They just provide the web interface and someone to yell at when there is a problem.
Businesses contract out services all the time. In this case, BankSimple is using some established company to store your money. They just provide the web interface and someone to yell at when there is a problem.