<p>It is an interesting argument and it was controversial when the practice started, from what I know of music history playing concertos started in the late classical/early romantic period and Beethoven for one felt it was a circus trick to have performers do it from memory (we know Clement had the music for the Beethoven violin concerto, he only got the final movement in the middle of the performance, because it hadn’t been finished yet!)</p>
<p>One of the theories about playing a concerto from memory is that it is less distracting, that it connects the performer with the audience, but as others have pointed out, sonatas are almost never memorized, and with a piano how distracting is having a score there, would the audience even notice? I have heard arguments the soloist would lose touch with the conductor if they didn’t memorize it, yet 20th century (aka “modern” concertos) are almost always played with a score by the soloist, I saw Joshua Bell premiere a concerto by Jay Greenberg and he used a score, and I have heard (but can’t confirm) that Hillary Hahn when she premiered the Higdon violin concerto played i with a score as well…</p>
<p>To be honest, I think memorizing concertos and such for auditions is more about the audition panel upholding traditions, of ‘this is the way we did it, so you should too’, because memorizing or not memorizing a piece has absolutely zero to do with the way someone plays a piece. The fact that musicians do so with modern pieces and with Sonatas and it doesn’t seem to hurt the experience so I find the argument about it being disruptive logically a bit dicey.</p>
<p>On the other hand, someone who is totally ‘score reading’ during a performance is ill prepared, because performers have to look up, to keep with the conductor, a sonata partner, chamber group members, and in an orchestra if you have the music mostly memorized, you can watch the conductor (I was blown away recently at the NYSOS programs at Carnegie Hall, all the kids were frequently watching the conductor). with a concerto the music is there as a guide and to allow them to keep their place, and if they do slip to recover easier IMO.</p>
<p>I suspect it is going to become a moot point in the near future, there are glass being perfected that would allow a performer to have the music in front of them without blocking the audience, the score could scroll on the screen on the glasses and be controlled by eye movements. The technology behind this is still in the prototype phase, but eventually it is going to happen, or they will have a kind of virtual teleprompter that to the audience is invisible, but to the performer appears right in front of their eyes I suspect.</p>
<p>Now another shiboleth, not clapping between movements, may need to be addressed:)</p>