People associate the concept of antisemitism with the Nazis and thus block out that it's possible to engage in perfectly ordinary civil-rights violations against Jews, like refusing to hire them or attacking them in the street.
Henrythere's this weird knee jerky reaction that "no of course they're not antisemites!" to any antisemitism, I think a lot a lot of people believe antisemitism is a thing that happened 1933-1945 and accusing people of it today is like saying they hate the Irish or own slaves.