Free speech is about the right to __articulate__ opinions and ideas. To articulate ideas and opinions, you have to think and formulate your thoughts.

What Facebook enables and optimizes for can hardly be called free speech. Articulation is not encouraged, merely the spreading of thoughts (both good and bad). Engagement has been optimized for advertising purposes. It led to banal agreement in the form of likes and reshares. There is hardly any discourse, people get silo-ed in echo chambers, and the extreme ends of the spectrum get magnified. Confirmation bias rules, and bad ideas aren't defeated by good ideas because they hardly come into contact.

So no, Facebook isn't enabling free speech, as much as they'd like to claim they are. At best they are a communication tool, nothing more.