Comment by tonymet

Postgres is essentially a b-tree with a remote interface. Would you use a b-tree to store a dead letter queue? What is big O of insert & delete? what happens when it grows?

Postgres has a query interface, replication, backup and many other great utilities. And it’s well supported, so it will work for low-demand applications.

Regardless, you’re using the wrong data structure with the wrong performance profile, and at the margins you will spend a lot more money and time than necessary running it . And service will suffer.