Once you know the principle behind it, you start to see the M&B fallacy everywhere. "Oh, so you're saying there's no racism in America anywhere and the schools should say nothing about it." I am trying to cast my mind back over the history I remember (reading history carries much more danger of receiving curated impressions) to see who used to use this in my formative years and how effective it was. I can't tell, but I think people use it more when they perceive themselves as in a position of power and are trying to discredit the attackers. Yet I can't be at all sure I am right about this. The modern equivalents would be "So you think we should do everything the government says, no matter what? No? Well then, you have to see that this is tyranny" versus "I can't believe you are saying that the government is lying about everything and we don't have to do anything about covid at all!" Sigh.
It's just tiring, and I swear it isn't getting any better.
BTW, in terms of "Karens" I have about an equal number of people I run into who have to tell me in the first 30 seconds that either "well, Omicron is basically just like getting a cold" or "most of those people are dying with covid, not from covid," versus people who immediately equate carelessness or resistance about masking with refusing to be vaccinated. We are clearly in a world where people are unable to believe there is a continuum of belief among those they disagree with, and perhaps even more worrisome, no continuum of belief among the people who basically agree with them. It is becoming a Marxist, or one-drop, or my sect-within-a-sect approach to all of life.
Resist this where you can, and please, not so much with the people opposed to you, because there are professional arguers who are making big money doing that. Apply it more to the people you generally agree with.