If you oppose "Multinational corporations", everyone knows you are using a code word, that you aren't making an economic comment at all, and that you are just being anti-semitic.
It's all in the decoding.
I don't think it's really anti-semitism but it is of the same dull-headed-brownshirt mentality. It's a McCarthyite word which like 'racist' is used to explain everything. Come to think of it, anti-semitism is also overused.