Humans need tests in all possible mediums to become greater. If you only take writing tests, You wouldn't be as good with oral activities, And vice versa.
Data that could conclude that there are more blind people than deaf people or if there are more deaf people than blind people COULD argue than one of them is worse, But those whose senses are not impaired need both kinds of tests anyway.
Now, What do we mean when we talk about tests? Well, We could talk about those in school, Or we could talk about tests that we run into in the natural world. But I argue that BOTH are necessary and, Really, Not avoidable in any way (except if you don't go to school). If you don't have either written or oral tests in school, You may be less advantaged for the tests that the outside world gives you, Tests that are more important to your life. Tests that school gives you, Meanwhile, Can help you prepare for the tests that the outside world gives you.
Some may argue that outside experience is more valuable than school experience, And, While I agree with you, NOT having school experience will most likely make the outside experience more difficult or even more traumatizing than if you prepare beforehand in school. So it checks out that tests in school are as good as those in the outside world.
The term "good" is subjective, But when I say good, I mean "able to support a human in a positive way. " Tests come in all shapes and sizes, But there isn't enough proof to suggest ALL tests negatively affect a human.