In a common IoT scenario, millions of devices will be sending data to your back end. It is possible that a large percentage of these devices could flood your back end for whatever reason. Few years back, I experienced it first had when a bad software update created a tsunami of requests towards a relatively scaleable back end, and caused an outage which lasted a whole weekend.
One approach (which I have been dealing with in the past few months) to prevent such flood on the back end is to create a so called "shock absorber" using a queue like message delivery system. More...