It depends heavily on what exactly you need out of a message queue. E.g. if extremely (extremely) high throughput is required and you don't mind dropped or lost messages, SQL may be a bad choice. But I've had a lot of success using Postgres-backed messaging.

Also your links are (mostly) from message queue companies who have a vested interest in your not using Postgres, or are from a time before LISTEN/NOTIFY and JSON(B) columns.