You have the right to reply but not the right to silence ................?

Most people would accept that as freedom of speech , so why do so manny try to silence ? Is it because they know they have already lost the argument ? Has society been irrevocable damaged by PC madness , do we now live in a world where the ignorant are legitimised in silencing the intellectual ? Have the key words of minority , race , gender , sexuality become a pseudo moral high ground , the hiding place of the emotionally crippled and intellectually inadequate ?