1. Facebook already knows everything you see and do on facebook
2. Facebook is the ad network and serves its own ads.
Therefore blocking ads on facebook won't prevent facebook from knowing everything you do.
GP seems to have a fair understanding of the situation, care to explain why you think it's wrong?
Well, it certainly replaces valuable data like how long have you looked at a given ad with either nothing, or random noise (e.g. if you draw a rectangle over them).
We are no longer living in 2013 where people posted about everything they do. Sure, plenty people do so still, and our interactions with that (even implicitly like how long we looked at it) is plenty of value in and of itself, but I disagree with the general notion.
The effectiveness of ads is that they can just throw stuff at you and "see" what sticks, without you ever telling a word.
When did you agree to be sold without representation and a contract, again? Something about malicious contracts nobody reads? Pretty sure that behavior remains...criminal.
Its been long documented that these systems are attempting to monitor you, even if you did not sign up for the service or interact with it.
I.e., you are categorically incorrect.
What you're missing is that, without good adblockers and possibly other tools, facebook also knows everything you do everywhere else on the internet.