The "Unite the Right" rally held in Charlottesville, the rally in which Heather Heyer was killed by a white supremacist, had ~20-40 attendees.

There were several thousand counter-protestors.

This is a Neo-Nazi rally in Germany: https://www.youtube.com/watch?v=D0ZPs48rKhw

Please describe, in your own words, how the restriction of free speech and association has curtailed the organization of Neo-Nazi movements.