Re: You don't need to know how 1,600 services work
While each micro-service may be simple, all that has happened is the complexity has been pushed up to the interactions between those micro-services (to some form or orchestration layer).
Maybe that allows Monzo to, at least now, to more easily manage that complexity. Or maybe having a greenfield development has just avoided the legacy complexity because Moizo don't have that much IT history.
Only time will tell.