The Rede was written by Lady Gwen Thompson who turned her family tradition into a tradition of Wicca independent of Gardner. The N.E.C.T.W. is largely to my knowledge based on her trad. Anyway, she wrote the rede in America, in the 1960s, and attributed as her adaptation of her ancestor Adriane Porter's teachings. This read is younger than Gardnerian Wicca, and it's tradition probably developed around the same time as Alexandrian Wicca. It was stateside though and had no bearing on Gardnerian Wicca, Alexandrian Wicca, Cochcrane's 1734 tradition, or those traditions descended from these. I suppose it wasn't until American Eclectic Wicca that this became widespread popular. But really it is not a part of Wicca and many Wiccans don't use it, many non-Wiccans do. Most Gardnerians I've talked to have said it's not remotely connected to their tradition. Valiente talks about it like it is in her book Witchcraft for Tomorrow, I don't know why she does, but I've seen some Gards say she added things and stopped being Gardnerian in her later writings. In short the Rede, which means counsel or advice, is not descended from the same sources as most of modern Wicca, and is not a requirenment for being Wiccan, and is not necessarily indicative of Wicca in general.