[duskwuff]

> FB slurps in all of the data that users voluntarily post.

That seems likely to be a grand understatement. FB has the opportunity to collect a great deal of data about their users beyond what they explicitly post -- for example, data about when and how they use Facebook mobile apps, how they interact with the Facebook web site, and what external web sites they visit which contain Facebook Like widgets.

[_jal]

Don't forget offline credit card transactions, FB and Google both.

https://www.bbc.com/news/technology-45368040

[dylan604]

But Google does all of this as well with its api/fonts/analytics/etc being used.