As usual, this paean to deductive reasoning (“formal methods”) leaves out its fundamental limit: how closely do the postulates and definitions fit the domain they purport to map? (“In theory, there is no difference between theory and practice. In practice ...”) My guess is that Jane Street maintains large code bodies where the mapping is 1:1, because the purpose of the code is to implement a deterministic algorithm. Many other coders work in such areas. But millions of us don’t: most UIs, most exploratory work, etc.
There is a movement parallel to formal methods to define acceptance criteria at high resolution but not logico-mathematically, which at least grapples with the mapping problem but can’t resolve it where the map isn’t the territory, which is most places. Has Google’s results page, with its extremely evolved internal optimization frameworks really hit an optimum? Could that prototype you whipped up to capture a hazy idea have better illustrated it? These questions are best answered by looking outside the system to what the system serves.