I found this reply unpersuasive.
By numerical point:
Hi, I'm new to this site so not sure if late comments are still answered...
The issues you raise overlap with relatively recent enthusiasm for discussing "natural kinds" in philosophy. It's a complex debate, and one you may be familiar with, but the near-consensus view in philosophy of science is that the best account of scientific categories/concepts is that concepts are bundles of properties that are/should be considered natural kinds based not on whether they are constructed or natural (a false dichotomy) but based on whether these concepts are central to successful scientific explanations. "Scientific" here includes philosophy and any other type of rational explanation-focused theorizing, and "success" gets cached out in terms of helping with induction and prediction. So the usefulness that you ask about can be grounded in the notion of successful explanations.
Here is a paper that discusses, with many examples, how concepts get divided-and-conquered in philosophy and science: https://doi.org/10.1007/s13194-016-0136-2. One example is memory—no one studies memory per se anymore; they research some specific aspect of memory.
Author, let me know if you want references for any of this.
Fair point, although I wasn't assuming any bad intentions, more like a hard-to-explain emotional intensity that seemed out of character for someone whose writing I am familiar with. But perhaps expressing my genuine surprise was not constructive—thanks. I removed this intro from my post.