It's a bit like asking whether road signs are effective for Americans who can't read. The signs are there for the people that are using the road, and if you're not using the road you can safely ignore it.
More like asking whether road signs are effective for Americans who are passengers in cars. No, it doesn't directly do her any good that they're technically accessible since she can't act on it, but it sure as hell affects her life that other people have access to the information provided by road signs.
I'm not sure the analogy works: roads were around long before writing, and there are still road users who can't read. That is why pedestrian crossing signals use lights in the shape of a person rather than written instructions.
