As for giving them a platform and an audience bringing more followers, firstly this is terminology used for justify soft censorship. Secondly in the UK back in 2010 Nick Griffin (a notorious anti-semite/racist and leader of the BNP) was allowed to speak on Question Time (a very popular show on the BBC). Afterwards we didn't hear from the BNP again because the ideas were exposed for what they were. The BNP party is effectively dead in the UK.
Almost every-time one of these racists are actually spoken to the vast majority of the population reject their message. Every-time it is repressed these ideas resurface because these people create their own echo-chambers and makes these ideas sexy as they are considered taboo.