We endlessly hear that ITIL is not prescriptive. Every organisation is different. We must adopt and adapt. Well... y-e-s.
There is a cultural imperative to fit "the way we do things around here" as much as possible, so as to reduce change, re-education and resistance.
There is a historical inertia due to entrenched incumbent systems.
But on the other hand the benefits of ITIL are standardisation and common language. Thess reduce the costs and time when new people come in: employees, trainers, consultants, auditors...