Think about written English: it’s phonetic.
How do you learn to RECOGNIZE A WRITTEN WORD when you don’t know what it sounds like, let alone what the letters mean. Or becomes a matter of a hundred thousand different symbols, recognized as a unit, removed from the auditory context.
I can’t imagine how any deaf person learns to read, to be honest . It’s an astounding feat.
And they wonder why they can’t compete with the iPhone