I think that less than one in a thousand (or 10k) discourse sites has come from Facebook. I’ve done over a hundred migrations from other platforms and zero from Facebook.
A message about Facebook that you replied to was seven years old.
Is it even possible to get your data from Facebook to do a migration? If so, and you have a budget, you can post in Marketplace.
I’m just a user here, but this isn’t really a place for complaining about other platforms. It’s for helping people use discourse.
If you want a place to complain about Facebook, it would make sense to create your own community for that.