It's disappointingly common for cloud-backed apps and device firmware to go into a hot retry loop on any kind of network failure. A lot of engineers just haven't heard of exponential backoff, to say nothing of being able to implement and test it properly for a scenario that almost never happens.

Even if you assume Facebook's own apps have reasonable failure logic, there's all kinds of third-party apps and devices integrating with their API that probably get it wrong. Surprise botnet!