Rhetorical moves like this are fiercely seductive, as all addictions are. But ultimately, they are lethal to any kind of rational argument. If "S" and "M" are merely stand-ins for positions in hierarchies we already deem bad, well, the outcome of our argument is trivial and frivolous: "S" is bad, and "M" is pitied.
What Satsuma said about S/M reminded me of this passage from Sonia Johnson’s “Going Out of Our Minds: The Metaphysics of Liberation.” She quotes Cheri Lesh:It is time to stop pointing fingers and making accusations. Time to look at something very hard and real. We are all crazy and weird about sex. Heirs to thousands of years of degradation and torture, of man as S and woman as M, of white as S and non-white as M, of God as S and human as M, of civilization as S and nature as M–who among us can claim immunity, who among us has not tasted the whip sting of poison in the honey, has not confused the slap with the caress? Sadomasochism is the basic sexual perversion of patriarchy.
Then Johnson continues:So in arguments for sadomasochism as a way of relating to others sexually, we must be aware that we each bear responsibility for creating an alternative to patriarchy that is an alternative. Hurting others/asking to be hurt, dominating others/asking to be dominated, humiliating others/asking to be humiliated–feeding the basic patriarchal addiction–is not finding an alternative. Instead, it is rationalizing and succumbing to the patriarchal imperatives most deeply imprinted on our psyches. It is fiercely seductive–as all addictions are–and it is lethal.
But this does not in any way hook up with the lived experience of people who have certain kinds of sex or become members of certain kinds of communities. Even if those communities and ways of having sex are bad or anti-feminist (for anyone who came late to the party, my view is that no, they're not), saying that there have been unjust hierarchies and then tacking a letter on to positions in them is not making an argument. It's saying "let's call this S and this M, and now we see that 'S and M' relate to one another badly. Now let's turn to this other thing over here, where people call themselves S's and M's. Same letters, same dynamic."
Which is what you're trying to prove in the first place.