The problem with motte and bailey is that it refers to two totally different things.
The first is when someone gives a definition of a word that no one could argue with– “God is just the happiness in your heart when you see a sunrise”, “rationality is systemized winning”, “feminism is the radical notion that women are people”, “my food philosophy is to eat food, not too much, mostly plants”– and then proceeds to argue using definitions in which God is omniscient and omnipotent, rationality involves perhaps dubious game theoretic and Bayesian claims, feminists believe that sexism exists and is bad, and your food philosophy won’t let anyone buy foods with more than five ingredients. It is good to point this out: “hey, you said I should be rational because I want to win, but now you’re going into all this Bayesian epistemology which I really don’t buy.”
The second is about group dynamics. It is the claim that groups tend to have members that are more palatable and less palatable to the general public, and that the latter tend to borrow credibility from the former. If you are used to “patriarchy” meaning “the overall system of gender roles”, then you may give unwarranted credibility to someone who uses “patriarchy” to mean “men universally hate women.” If you are used to Thomistic theologians, you may take Josh McDowell too seriously. If you are used to people who use “rationality” to refer to a series of heuristics that help you come to the correct conclusion, you may pay too much attention to Singulatarians. Et cetera.
The problem is that group dynamics have literally nothing to do with whether ideas are true.
Imagine a creationist arguing with an evolutionist. At the end of the argument, the creationist pulls out her trump card: “a lot of the people reading this argument don’t care about science at all! They don’t understand anything about evolution; I could easily beat them in an argument. They’re just looking for their ingroup to triumph over their outgroup and signalling that they’re rational and science-minded individuals.”
Forgive the evolutionist if he responds with “So?”
The creationist’s point is true: this is, in fact, an accurate description of many people who read creationist/evolutionist arguments. It also doesn’t matter. Evolution would still be true even if all creationists were disinterested yet misled searchers for truth and all evolutionists were motivated by their ingroup winning. This is pretty obvious.
And yet the second use of motte and bailey borrows credibility from the first use. “Motte and bailey” is filed in the “logical fallacy” part of people’s minds. It feels like saying that someone is using a motte and bailey is a devastating counterargument, even though in reality it is just making a statement about how social movements work that is true of literally every social movement that has ever existed or will ever exist.
This is bad practice. Reserve observations about social dynamics for conversations about social dynamics. Do not attempt to use them to win arguments about object-level issues.