The inherited framework
Much twentieth-century Wiccan material is built on polarity: a Goddess and a God, a High Priestess and a High Priest, a symbolism of fertility and heterosexual union running through the Wheel and the Great Rite. That framing reflects the mid-century milieu it was composed in, including ceremonial magic and the folklore theories of the day.
What polarity was meant to describe
In its own terms, polarity describes creative tension between complementary forces, with male and female as the primary image of it. Some traditions treat that as essential to how their ritual works. Others read polarity as one image among several, or as being about difference rather than about bodies.
The challenge to it
From the 1970s onward, feminist and Dianic groups reworked the Goddess-centred material, and gay, lesbian, bisexual and trans practitioners built traditions and covens where polarity is optional, reinterpreted, or dropped. The Minoan Brotherhood and Sisterhood, founded from the late 1970s, are documented examples. Plenty of eclectic and solitary Wicca has quietly worked this way for decades.
Where Pretty Little Wiccan stands
Biological-essentialist claims, that Wicca requires a particular body for a particular role, are one position within Wicca, not a universal Wiccan truth, and some groups holding them have excluded trans practitioners. We present polarity as history and as one live option. Your gender does not determine what you may practise.
Reading the Great Rite in this light
Understanding polarity explains why the Great Rite is framed as it is: it is the fertility symbolism of the tradition made explicit. Knowing that makes it easier to decide whether that symbolism is yours, to reinterpret it, or to leave it in the history section.