Facebook and twitter - all social media for that matter - are not open news platforms. They do not provide an unfiltered public soapbox. We have confused social media with the free press. The algorithms employed make each feed essentially a private bubble. This is a good thing as it closely models a face to face conversation amongst friends. This is not a flaw, it is by design. Note the word 'social' in social networks.
In person, you know, real life, if someone bashes into your conversation with, "I couldn't help overhearing" and proceeds to spew a complete load of shite they are immediately and without deliberation considered assholes and are shunned.