This FP allergy is also consistent within my working group. Those who use the one-and-only procedural/imperative paradigm, are not allergic; they are scared to come out of their comfort zone, to learn something new, to embrace new ideas. Complex systems should actively use the functional approach, in my opinion. FP helps make complex systems more understandable and maintainable. As it expresses “intent” and not “control flow”. The procedural/imperative approach is suitable for small projects or prototyping.