[candiodari]

This.

How much of the anti-formalism attitude is about real difficulties of the method, and how much is about "I don't know this method, so it must be bad".

Code, regardless of what it does, is a state machine. That does not change whether you do it intentionally or not. And if you don't use state machine design tools to design them ... then your state machine becomes a huge mess with transitions going from everywhere to everywhere and very surprising connections in many places (and most/all of those will be bugs, bugs that no unit test ever is going to find).

Which seems to be acceptable for a lot of people.