Grammar is essential for communication. All languages have grammar rules, whether they are formal rules or informal patterns. If the basic rules are not followed, we are unable to communicate. Here is a simple example we encountered recently. A writer typed experiences shows for the subject and verb in a sentence.
Most grammar checkers can detect that error.
The reason that the grammar checker points out the problem and asks the user for a solution rather than making its own correction is clear. Only the writer knows. A computer program doesn't. Even another person doesn't. So until we create mind-reading software, grammar checkers will continue to ask questions.