[lolc]

Your first two links don't contain any technical information about the "fbclid" parameter. They can be read to understand why Facebook does it, but not how. I see how it is useful to get this info when I'm paying Facebook for views. But that's something different from understanding how it works. So articles like this are needed to piece together what is going on.

Now the interesting question will be whether "fbclid" can be tied to individuals. And I couldn't readily find this info in the links you posted. Maybe I'm bad at reading?

[kolmogorov]

This will most likely be the same as gclid for AdWords . You can’t tie it back to individuals for gclid and I’d expect the same there .