[joseph8th]

I think you have defined "queue" too narrowly in the context of the OP article. MQs are one thing, but the article is about queues as data structures.

A directory of files to be processed may be treated as a queue. Add several directories for different stages of processing, and you have a rudimentary state machine.

Distributed systems in particular may benefit from an MQ, but are by no means necessary.

Generally, when we add an MQ we are really regulating an already existing implicit queue. It's such a common and intuitive data structure that one may easily create one without even realizing it.