Before all that - and you are right on your take - there is a more basic flaw that affects social media: people do not know how to act properly.
The anonimity emboldens the small minds that use it to mistreat, slander and ridicule others and spread lies and rumours.
Unless we can force people to act with civility - which implies people being fairly conscious of the consequences of their words and actions - social media will remain what it is: a cesspool where the worst of our species destils into a refined poison.