Those horrible people still exist either way, they just dont say out loud what they think. You dont restrict people thinking that way but people talking out loud about it. The no platform approach was rather successful in Germany when it came to pushing the extreme right out of the public discourse and banning their parties. But that only works as long as they dont organize a platform of their own. Then you have a far right party rising into parliament and entering as the second largest party in some states.

People dont change you just filter them from your view of reality. And its no surprise people who bothered to look knew rather well that they existed.