Much of the Jewish community came from Eastern Europe during the period 1870-1910. During this time it was well documented that many clerics with backing from local potentates (politicians) would spread blood libel and in much of Eastern Europe is was common for Easter services to be concluded by stoning the local synagogue or worse.
That is correct and that is what thrust them in the arms of being sympathetic to Communism, and the Bolsheviks protected them from the Pogroms if my memory is correct. In many ways todays Reform Jews here in America are still carrying great great great ( how many more?) Grandma and Grandpa’s baggage with them in terms of political leanings... Compound that with all the intellectuals of Jewish decent who’s philosophies they may mave absorbed that still might be controversial (from late 1800’s and early 1900’s) and their maybe a lot to let go of.