In my experience, treating people as individuals not always is practical. I mean, you might not have time to write a long explanation, or even explain in person. It can also happen (quite frequently) that the person you are addressing is not willing to listen. You you sum it up nicely in just a word. Google said that “Karen” means a whole set of behaviours associated with a certain type of “white women”. It seems that, like boomer, Karen gets a lot more reaction than long explanations about how some complains to the manager are out of place or that they are obnoxious, etc. Sure it is not “nice”, but it is still treating them as individuals in the way that they don’t go around calling all white women or even all middle aged white soccer moms that. Just the ones that are being obnoxious from their point of view.

But since you mention “intersectionality”, I would say that it is more telling that there is not a “Kevin” version of that. Or maybe that is covered by mansplaining. Not sure. Point is, expecting people to treat you as an individual is a providledge on itself. I should know, since many times I’m treated as “all women”. People treat others in broad terms all the time. Taking the time to know, understand someone takes effort. That an extranger demands that from you shows privilege. Even the fact that they demand “the benefit of the doubt” when some groups get always the “assumption of the worst”, is another. And so on.

Basically they are treating you the same they treat everyone else for once. Denying privilege is not attacking or treating you badly, is neutral. That is basically the point. You actually think that in the middle of their day they should stop and patiently explain to someone who has treated them badly why it is wrong to just be ignored most of the time is “productive”? For who? Not for them. On the other hand, calling them “Karen” might get the job done in just one word. They send the message across and save lots of time and effort “that person is being obnoxious, etc”, the fact that obnoxious person gets offended is not their problem. In fact if you are consistent on the “if you behave bad I would make you feel bad, call you out”, you might taught them that behaving badly has some consequences, etc. So I would revise the “is not productive”. Not for you, but it clearly is for them.

Speaking from experience, not everyone values if you are nice. Some people take that for granted and only react to other approaches. Women’s suffrage weren’t earned by being nice and treating men like individuals, to put a simple example. And I’m saying this with a lot more chances to be called “Karen” than you, since I’m a white woman. XD