Because you'd be wrong.
And if this blows your mind, then check out every link in that thread.
Guess who are at the forefront of trying to shut down methods which provide a bridge to independent typing: ABA people.
"Ew, no. My child is not like you awful people. I won't let my child turn into your ilk."
#AbleismExists
But ableism teaches parents that non-speaking communication makes a person less worthy. ABA promises those parents that with persistence, their child will become more worthy.