It is simple, really: There are also many piano players who cannot make confident and accurate movements on the keyboard without looking at their hands! My process learning how to type on a computer keyboard without looking was very much like the process I experienced while working on my piano skills over the years: You graduate from fumbling with your hands and exhausting switching between looking at your hands and the sheet music to sight reading to playing with your eyes closed (if you want to). Though a lot of advanced players can and do play without sheet music and sight reading at all, interestingly, a lot of those players then keep looking at their hands instead! because the music progression is strictly following their mental model of the piece.