I don't think „don't giving them platform“ works. Soviet union worked hard to give no platform. Yet people invented all sorts of background channels. From book printing to discussion clubs to underground music shows. And when the system cracked just a bit, it washed away the system. While many people, both inside and outside, were completely unprepared for that. Because if stuff is hidden under the carpet it ain't happening, right?

Same pattern with Brexit or Trump.