It is rude to read your score whilst playing your instrument.

At least that's the story reported to me by a violinist friend who went on holiday to a remote part of Greece (30 years ago). She befriended some local old violinists (who knew how to play their local folklore, but knew nothing about Mozart or Beethoven) and invited them to a chamber music concert. It's the first time these musicians went to such a performance. Their comment was: "It was very nice. But these classical musicians are so rude! Whilst their play on stage, they read books!!!"

It's not necessary to read music in order to be a musician. Music is a gift which can certainly be worked on, but it is a gift, and can come in a variety of forms.