To me, "from first principles" implies a certain presentation style that's different than what this article employs. It feels like you take it to mean "start from the axioms and build up without any gaps or unanswered whys" which is fine, but it turns into a laundry-list of topics the reader needs to get through before seeing the payoff, which in a way is no different from any other math text. I was expecting a more reverse-engineering approach where the first principles are derived from analysis of the problem / application, and we proceed from there.