Before I begin, what I am about to write has absolutely no relevance to Halacha. None.
I recently gave one example (here)of a Rishon who took R. Meir’s explanation for Hilchot Niddah as normative rather than homiletic. I was reminded by a friend (h/t Shaya) of a radical position in the Achronim that takes this farther. Again, R. Meir argues that the laws of Niddah and the distance created are supposed to increase the desire a husband has for his wife. On the basis of this, the Toras HaShelamim toys with the possibility that the laws of Niddah would not apply to unmarried women. He notes that there is a general machloket between the Chachamim and R. Shimon if darshinan taama dikra, if (for simplicity) we allow the philosophy behind mitzvoth affect their practical application. R. Shimon does. If so, he suggests that if we rule like R. Shimon (against most Rishonim), and accept R. Meir, a women who is not married would not be restricted by the laws of Niddah. It should be noted this position is not accepted Lihalacha even by the Toras Shelamim, as he relegates it in the end to a rejected position in the Gemara. Furthermore, every other authority rejects it out of hand. Lastly, even Toras Shelamim admits that now that we treat all Niddot as safek Zivot, the reason would not apply. Still, it is another potential example of this piece of homiletics being taken too seriously from a normative perspective.
The passage is available: here.