torah study - Women and Oral Law

I see that there are numerous poskim who permit women learning the Written Torah, but not the Oral Torah. What I don't understand is that you can't understand the Written Torah without the Oral Law, and can't, in fact, fulfill the mitzvos properly. Are women supposed to be tzdukim/shomronim/karaim? All of these are groups that our sages consider outside of normative Judaism. But surely Jewish women must be within Judaism, so...