Nit: the application the author describe doesn't even publish the request using RabbitMQ, as far as I can tell—they publish the request with a simple HTTP request. They use RabbitMQ solely for scheduling the "Check if this task is done yet" job every ~5 minutes. I haven't used RabbitMQ myself, but it does sound like kind of like a square peg / round hole situation to me.

I was also surprised by that but there may be some slightly unusual background reason for that that simply doesn't get mentioned. Superficially it sounds like the author should just... do the HTTP request? Since they're waiting for the response anyway

Almost twenty years ago, I was on a team that built a bunch of health care apps where we had significant, robust mainframe business systems that we needed to get in front of both internal staff, external providers, and the public. So yes, those systems definitely used a whole lot of messaging and in my career since I saw repeats of those patterns not only in that industry, but also financial services, telco, and lots of other places I stopped along the way. Anyplace you’ve got hulking business systems with lots of rules, it’s common to have messaging in between there and the web, and for various distributed applications to talk to each other.