how dominant public space used by mediocre people

Why the media who set agnda 4 discusion intolerant towards contending opinions. May v have to reread 'manufacturing consent' by Chomsky. Is twitter is an online space 4 'hi', 'bye' chats? Or more of a virtual public sphere as J.Habermas opines. denying the serious discussion/blocking is antithetical to the basis of communicate rationality as Hebbarms say.