I knew I’d read something else rather relevant to the whole Facebook fiasco – the thought that the decline of Facebook could act like the spread of a virus (the explosion of inactive or deleted accounts being akin to the growth curve of a pandemic). Here’s the article in the Guardian newspaper from 2014:

https://www.theguardian.com/technology/2014/jan/22/facebook-princeton-researchers-infectious-disease
And here’s the study from Princeton (Epidemiological modeling of online social network dynamics) that the article quotes:
https://arxiv.org/pdf/1401.4208v1.pdf