Crimson Longinus
Legend
"All animals can be divided into three categories: Vertebrae, Arachnida and Metazoa." Very useful!It's not useless. I can use it pretty easily to differentiate between gamism and narrativism, for example. What you're saying is that the Kingdom portion of taxonomy is useless because it only says Animal and can't tell me the difference between a platypus and an elephant. Okay, that doesn't make it useless. But the essays on the S in GNS actually do go to a higher detail and talk about different ways it can function while retaining the one large scale differentiable trait.
If one category applies to effectively every instance to the things being categorised, it is useless as a categorisation!