A queue is a thing to be managed carefully when designing systems:

- you need to ensure that your producers don't produce at a faster rate than your consumers can keep up

- if the consumer is unable to handle the request now, queueing it and handling it later is often not the right thing to do. Most likely by the time the resource is available the nature of the request will change.

TCP itself is already a queue. All these message queue systems also make the silly decision of layering their own queueing on top of TCP, leading to all sorts of problems.

Basically those things only sort of work if you have few messages and are happy with millisecond latency.