My take: 

1. 19th-20th century Holocaust&Pogroms were unprecedented thing
2. So once survived, Jewish people should - created framework of enquiry and also relation/bridge building (right away)
3. What is this anti-semitism? (systemic, thorough enquiry, pursuit) 
4. How, then, Jewish (as a human group) can form, build relation, bridge with other human beings, human groups? How that can be done and pursued? (I think there is something really stupid, and comical about the nature or root of anti-semitism. It’s a hatred based on rumor and cheap ‘overheard’ stereotypes.)

These are my constant (unsophisticated, unrendered) intuitive take on this question. These can be made more ‘matching’ to what actually followed as reaction among world Jewry in 40s, 50s, 60s, and 70s (which is also severely in short of any thorough, comprehensive tracking. ) 

But Israel nor world Jewry never got into this kind of fundamental reflection. Few potentials - Kurt Lewin, Adorno - but they never pursued their enquiries with humility or in the spirit of collaboration. (Arrogant 19th century social science model.) [*Another thing is like - how actual ‘war’ Israelis had to fight through for independence - towards Palestinians and surrounding Arabs - how those acts and outcomes shaped and hardened ‘the world’ Israelis have to live in. Cruelty or aggression one has to exercise could limit and bind self. That might prevented Israelis or Jews to really enquire about the question of antisemitism and relation/bridge building with other human groups.]

And - PS: Based on my experience with European and American Left - I believe it’s mostly driven by anti-semitism, hatred towards Israeli and Jewish people. [*Which can coincide and run parallel with sympathy and sense of justice for Palestinians.]

Some ‘intellectualized’ Jews - few of them live in denial about this (without actual experiences). But ‘one person’s very convenient, compact, ‘intellectual’ but subjective thought - can’t be credible by it alone - when there is something this collective persisting among human beings.