Current secular scholarship on the Crusades says that this legend is false. The streets did not run with blood. The “massacre” was hugely exaggerated in the chronicles.
Does that mean the victorious Crusaders were perfect little angels.
But the first rule in historical research is to evaluate sources critically. It is common for accounts of military victories to be exaggerated.
Regarding the massacres of Jews in some times in Germany. This was mob action; the bishops did their best to protect the Jews. Socio-economic issues as well as religious issues were involved.