No-rewrite correction is especially important for prompts, because prompt wording controls the task. If a checker adds instructions, changes constraints, or rewrites the request too broadly, the AI response may solve the wrong problem.
It also matters in professional communication. A client update, support reply, or manager note may need to preserve careful wording. In those cases, grammar mistakes should be fixed, but promises, timelines, and responsibility should stay exactly as intended.
For personal messages, preserving voice can be even more important. A technically perfect sentence is not always the most human sentence.