Mainly I see categories as useful only as “shorthand”, and then only along very particular vectors.
For example, one category that includes people like me (at least along one particular axis) is “female”. To me, all this really means is that I’m physiologically configured in a particular way that influences what kinds of bathrooms I can use and what kinds of doctors I need to see. In that respect, “female” is a useful and descriptive category.
But in other respects, it isn’t at all useful. As a youngster I went through a phase of “not seeing myself as female”—not because I hated my physical form (I don’t) but because everything that people seemed to associate with “females” didn’t fit me. As a female, I was expected (by my surrounding culture) to like pink things, to want to wear dresses, to prefer “domestic” games to construction toys or computers. I was also expected to have certain kinds of social skills I didn’t have, as well as certain cognitive tendencies. Etc. So my initial reaction was to wonder whether or not I was a “real girl” in the first place.
Eventually, though, my brain did a sort of flip and I realized that the problem wasn’t that I was “inauthentically female”, but that people were taking the things about me that were actually female (e.g., aspects of my physiology) and using those things as a basis for assuming a whole bunch of other things. And my reaction was one of indignance at that point: why can’t a Real Girl play with the spaceship Lego and wear pants on special occasions (instead of annoying, uncomfortable dresses)?
So, I’m quite familiar with the phenomenon described in this post. It’s actually kind of surprising to learn (as I have fairly recently) that many people actually memorize a category definition and then attempt to force-fit reality into it, rather than just gathering a lot of data over time and then (when necessary for the sake of practicality or shorthand) applying category-labels to some members of that data set along particular specified vectors.
In other words, if I’m applying for a job, the fact that I have ovaries shouldn’t be a factor (unless the job happens to be something like “egg donor”, but that’s not something I really see myself getting into). But if I suddenly start experiencing weird abdominal pain, the fact that I have ovaries (and other female internals) becomes pertinent information. The category is context-specific and I think a lot of problems come in when people try to “universalize” categories across all contexts and along all vectors.