That is all true. In some ways it's a bit late to stop it now. Once info is out, there is no taking it back. They can be cut off from gathering new data but they still have huge stockpiles that haven't even been processed yet.
It is not just intelligence agencys, it is very big with corporate marketing. Well, any marketing. Some of the google analytic data that is tracked is very disturbing. Google, and Facebook, and Microsoft, and most others, build and share detailed profiles on customers that sometimes includes very personal details.
People don't realize how much they are telling when they sign up for grocery club cards, amazon accounts, and anything else that ties data to an identity. They're not giving you deals for free. Nothing is free. And none of that info is protected.
At some point, all of that will become public. Either through slow dissemination via sales, marketing, and data analysis, or sudden bursts when there are leaks.
It can only be spread, never removed.
Pandoras Box!
I uninstalled that stuff this morning. But I hear Facebook has almost always been treated as a data-mine by intelligence authorities. If anyone is concerned about privacy I'd suggest getting rid of it.