It feels ai-written, for sure. The sentence structure and idioms are very typical of ai writing these days.

Agreed; I don't think "Not X, but Y" is a reliable tell on its own, but taken as a whole TFA set off my AI writing spidey-sense big time. The intro takes three paragraphs of fluff (ironically) to say "My product used to have long docs, but after using a product with much shorter docs it made me reconsider my approach."