Greer suggested that - I don't know if I'm allowed to use this word on MN but when The Female Eunuch was written in the 70s it was 'transexuals' - idolised an idea of femininity that had virtually nothing to do with real female bodies. This goes for drag artists, too. It's not really connected to women; it's a hyper exaggerated simulacra of a sexually available pre-pubescent female. (Red pouty lips, impossibly pneumatic breasts, hairless, airbrushed, huge-eyed). A porny sex-doll, I suppose.
I expect this is where some of the anger comes from. Women don't look like that. It all ties in perfectly with the capitalist patriarchy - the effort required for girls/women to try and achieve this deliberately impossible ideal (and measure our self worth according to how closely we can simulate this abstract idea of 'female') is a useful tool.
So the impossible picture of 'woman' (nod to Purgatory's excellent posts on Platonic Forms the other day) is created and then used as a stick to beat women with for failing to live up to.
This was the idea of the 'third sex' Greer posited - probably what we'd call the feminine gender/stereotype. At least, that's what I recall from the book, which I read a long time ago. It's deliberately impossible, only achievable with the help of implements, tools, paint, surgery, expensive treatments, photo filters, lighting, airbrushing, etc.