Facebook is a "Public Square"? Please. Call a spade a spade... it is a "Walled Garden". If you don't like how the roses are starting to smell, well, step outside the gates, no one is keeping you in:
https://www.newsweek.com/facebook-tracking-you-even-if-you-d...
That being said, the "public squares" in many big cities are almost exclusively the domain of scammers, pickpockets and the insane. So maybe the parallel does make sense.
"If you don't like it, leave." is more like a religious mantra than a serious normative argument at this point. Did we mention the trackers?
Personally, I just don't go, and so I miss out on the benefit I would get, but that is the price to pay at the moment.