It's the existence of UB that is the reduction in precision. A language without UB is more precise, in my view, than one that has UB. I don't know if this a conventional view. But being able to write parsable, compiler-receivable code that does 'uh, whatever', feels like a reduction in precision to me compared to a language that does not have that property.

Otherwise, we're just saying that the precise parts of the language are precise, which isn't much of a differentiator since it's similarly true for all languages.