There was some short Ted Nelson video I watched a while ago (I'm afraid I'll never find it) where he made this claim: they needed SQL and a separation of concer

There was some short Ted Nelson video I watched a while ago (I'm afraid I'll never find it) where he made this claim: they needed SQL and a separation of concerns (i.e., DBA) to build up a financial system where it was hard to embezzle money. And it's not JUST ACID and transactions that you need (though you definitely need those things!) but also the ability to audit access to the database-of-record, which SQL gives you. Maybe the corollary is that you should build up an appropriate domain DSL so that you can express your important claims or transactions in a comprehensible way. It's not to say that you can't misimplement the DSL to your advantage, but there's an implicit good-faith claim you are making that is different from raw vertically-integrated code.