The devil is, as always, in the details. I think "make invalid states unrepresentable" is a good thing to teach in order to push back against spaghetti code. State management is hard, and untangling bad state management is near impossible.

But of course, some flexibility is often (not always) needed in the long run, and knowing where to keep the flexibility and where to push for strictness is an important part of skills development as an engineer.