Personally I've always found it quite antisemitic to prescribe all people of the Jewish faith the opinions of the state of Israel, and in turn hold them accountable for the states actions.

When people say anti Zionism is equivalent antisemitism that's what they are doing, and in turn removing all agency from people of the Jewish faith.

I have yet to ask people who make the argument about this though, but I assume it'd be a shitstorm.