Facebook will still harvest your personal information to profit from. They'll just do without your involvement. They'll get it from anyone or anything you've ever revealed information about yourself to.
Australia needs something like the GDPR, can't happen soon enough. I enjoyed the wild west days of IT, but I think now companies are enjoying it a bit too much.
It doesn't help that legislators wouldn't have the foggiest clue about some of these issues^, so there's no impetus from the legal community or political arena to make changes, while nefarious companies are doing whatever the hell they like.
I deleted FB years ago, and this infuriates me to know they might still be trying to sell my information based on contacts and what I share with them.
^ Actually, they've recently tried to pretend they are above the law of mathematics, so...