I wish postgres would add a durable queue like data structure. But trying to make a durable queue that can scale beyond what a simple redis instance can do starts to run into problems quickly.
It would probably work fine, it would also put the jobs at risk of people who managed to convince their enterprises that a dumb but fast server (Kafka) was actually a good idea.
Also, LISTEN/NOTIFY do not scale, and they introduce locks in areas you aren't expecting - https://news.ycombinator.com/item?id=44490510