I have not attended a concert where the music is played from the score, but then I live in a very small town with only a few performances. I would personally have no problem with it You might want to look at this New York Times article, as it lists several concert pianists that play from the score other than Richter https://mobile.nytimes.com/2013/01/01/arts/music/memorizations-loosening-hold-on-concert-tradition.html Also add Yundi Li to this list