tl;dr They were, until Christians came around. They were looking for analogues in the old religion in order to assist with conversions. Freyja, being Odin's wife was the best candidate to be the Virgin Mary analogue. But, you can't have your Virgin Mary analogue being a sexually promiscuous witch. So, the "negative" aspects of the Goddess were pushed onto Freyja, and Frigg was created with the "positive aspects", to become the Virgin Mary analogue to assist with conversion. The pagans managed to sneak weaving into Frigg however, and to the pagans, weaving and cloth craft were associated with magic. The Christians never knew!