Sorry maybe I didn't express it correctly but my thoughts were that nobody believes the right to make sounds from our lungs or put words on a page are fundamental - what is more important to us is that our views and opinions are heard by others and that no authority can choose for us what we hear. Living in this way gives us more freedom to choose how we live and allows us to decide who to be influenced by.
Now take the example of promotion of terrorism - it's possible to argue that by allowing someone to post certain types of messages to a group on Facebook, they are creating an undue influence on the people in that group. For example by asking his followers to reject the views of outsiders (a common tactic in many religions, cults and conspiracy groups) a terrorist could be argued to have taken the freedom to hear other viewpoints away from his followers.
Now you can of course say that any terrorist or religious or cult leader is acting within a system of free speech - no one has technically had their freedom taken from them. That is true, but the reality of how humans choose who and what they listen to create the same effect as if they had lost those faculties.