But that's not actually true. It's very common have to have a program that is valid and won't pass the borrow checker. You need to adjust the way you program t

But that's not actually true. It's very common have to have a program that is valid and won't pass the borrow checker. You need to adjust the way you program to generate programs the borrow checker will approve of, and then the 10% is when it's hard or impossible to make that adjustment. It's fine, it's just that it is more restrictive than the philosophy claims. It's still a good approach.