The countries that don’t do that still have freedom of expression (and they tend to have human rights protections even more expansive than ours), it’s just that it makes no logical sense to hide nazis (whose politics amount to advocating against human rights for particular people) under the skirts of human rights protections.
The paradox of tolerance states that if a society is tolerant without limit, its ability to be tolerant is eventually ceased or destroyed by the intolerant.