Sarah McLachlan is another musician who can definitely compose/ read music. Theory is actually pretty easy once you learn the mathematics of it. Beethoven was able to continue to compose because of this.
My sister went to school for music and she explained how Beethoven was able to continue after he went deaf and she said it is actually quite easy once you have the mathematical understanding of music composition. I just smiled and nodded. I can read music but do much better from hearing a song then playing it on the piano. From there, I can write it. I can't listen and compose to sheet.