Jewish leadership was non-democratic

The rulers of the host country invested power into those members of the Jewish community who could harvest from the native Jewish population the most value for the monarch. The court Jews therefore had to be either the wealthy or from the traditional/rabbinic leadership. The non-democratic character of the Jewish political structure was thus built into the diasporic nature of Jewish politics. 

Anti-Semitism was built into the construct of the politics that bound together the host rulers, the leading Jews, the host populations, and the Jewish populations.