For reasons perhaps hard to explain now - sometimes things are just of the moment and defy later explanation - there was a period in the aughts when making facile Nazi comparisons was considered to be an unexcusable form of anti-Semitism. I think that was wrong in degree, in that I think one can make facile Nazi comparisons without being guilty of being an anti-Semite, but I think the general point of "it's more than just rude to make facile Nazi comparisons, so avoid doing that," was correct.
Anyway, things change, not necessarily for the better. Everyone conservatives don't like is a Nazi, but the liberal Nazis, not the conservative ones, who they support.