This leaves out your ear--
Agreed. Sight reading is made MUCH easier if you know what the passage will sound like before you play it. You can also hear if, as you sight read, if you are missing an accidental, a rhythmic component, or if you flat out played a wrong chord. It almost lets you predict what comes up without stopping to name the note (in music that isn't completely ape sh*t all over the piano banging random clusters )