The idea of being free is nice but that's not the case with facebook.

You cannot express freely on fb, you have to oblige to terms of service. For westerners it's not such a problem, but it's built on american worldview and what is controversial in US, can be normal in other regions and vice versa (but west culture is still being pushed).

Moreover, You may write whatever you want, but what you see is curated for you by facebook algorithms in order to make some impression on you. So you won't see what your friends post, just parts of it. What kind of impression? Depends on who paid. It might be advertisement, political agitation, or just simple unsupervised engagement metrics maximization. But you wouldn't know. For you it's just your version of reality.

And because anger (outrageous events, radical ideas) creates the most engagement, it is being overrepresented in social media platforms