[tedmiston]

This is an excellent summary.

I don't think you missed anything substantial... but I'll add two extensions:

(1) Social graphs change slowly. And they still own Instagram, so for many users they have a live social graph still.

(2) Facebook Pixel is dead. Long live Facebook Pixel!

The Facebook Pixel is now (or at least nearing) effectively dead on modern up-to-date devices running ad blockers. Of course that leaves plenty of desktop machines where people aren't running ad blockers.

But more importantly, Facebook has acknowledged the elephant in the room and moved from client side to server side with Conversions API (CAPI) (aka the new "Facebook Pixel"). And there's nothing ad blockers can do about server-side analytics...

[HWR_14]

I left out Facebook Login. That may be a help as well, although I don't think they get much from that they don't get from the other integrations in mobile apps/websites already.