Imagine you have recipe for Pizza Margherita.
A really, really good Pizza Margherita.
Some folk use it to make Pizza Margherita. It's damn fine pizza. They're happy.
Others hold the basil, add mushrooms and broccoli, and still call it Pizza Margherita. Some people like it. Others do not.
Others give you a cheese and tomato sandwich — and tell you it's Pizza Margherita. Some people like it. Others do not.
Others tell you the Pizza Margherita recipe describes all possible Italian foods.
Others tell you that you if it isn't Pizza Margherita then it isn't Italian food.
None of those things mean your recipe is a bad or that Pizza Margherita is terrible.
(Replace "Pizza Margherita recipe" with "Scrum Guide". Or any other set process description. Discuss.)
(Variation of an old twitter thread — it had more animated GIFs)