It is not the only reason. In swing states like Michigan it seems to have been the deciding factor.
https://www.newsweek.com/jill-stein-wins-22-vote-dearborn-gaza-stings-harris-network-1979861
However i doubt that even with a decent campaign of addressing the economic concerns of normal people the Democrats could have hacked it. With the steadfast support for Israel they have shown everyone whose ancestry is somewhere south of the European alps, that they are second grade people, easily dispensable if necessary.
It depends. You have clubs that give consecences for this kind of behaviour and clubs that downplay and ignore it. You have fan scences where these people are a small minority and you have scences where they dominate.
It is never black or white, but a spectrum. In the case of Maccabi fans it is a very dark shade from what i have read now. Especially as they have many ties with the IDF and are openly celebrating the crimes if not partaking in them personally