Frankly, I disagree. What she describes is an idealized usage of the slur that's only ever used to punch up. Anyone online knows that the term is rarely used in such a way. It's virtually always used either sarcastically, mockingly toward women or as a very intentionally used term to try and undercut a woman's perspective -- particularly when they're speaking boldly or with emotion. Sure, most usage of it is completely innocuous. Until it isn't. The misogynistic overtones very often smother any potential value in examining privilege.
Of course, it says so much more that this perspective, that "Karen" is both good and progressive, is mostly repeated in male-dominated spaces like Reddit or, well, here. The communities where women's voices are more predominant -- a good public one would be Reddit's TrollXChromosomes -- agree that its usage as a slur is all too common. Of course, even in feminist spaces, there's a good conversation going on about it. For example, on TrollX right now...
link.
That said, it doesn't dismiss how fucking gross the pushback against the term is as a parallel to worse slurs.