Im honestly unsure if you mean this as opposing "doing everything in Postgres" or as opposing "throw more services on the stack".
Because both are true for the statements. You have that complexity, regardless of where you implement it. Either you are building the rube-goldberg machine inside of postgres out of modules, config and SQL or outside of postgres with additional services.
The only way to really solve this is to avoid building that RG machine in the first place. In this case: don't have queues. In practice that probably means introducting complexity elsewhere, though.