To some elements of the the modern left (i.e. Antifa), it seems like anybody who does not agree with certain ideologies, such as "Equality" (in the Identity Politics sense; again "Equality" has a fuzzy meaning), is equated with being a Nazi.
To paraphrase what I wrote above, the White Nationalist (aka "the Nazis") movement only gains followers due to the prevalence of Identity Politics being used to affect policy benefiting certain minority groups. White Nationalism is Identity Politics for White People; seeking to use politics to benefit White People and/or creating a white ethno-state. Are you seeing the connection?
Is this any different from groups such as La Raza, the Black Panthers, or any other ethno-state group? If so, how?