Sophia pianoloverus can't imagine virtually any of them saying that they have to memorize music because playing with the score is so difficult.
My point is, that once again you are singling out advanced players/professionals as being "different". The above sentence can just as easily be applied to novices/amateurs.
There have been very many posts on PianoWorld and on this forum(and even on this thread) where the poster has said they have to memorize music because their reading is so poor that playing with the score is far more difficult. None of these posts have been from from advanced players. IOW when you say this sentence can be just as easily applied to novices/amateurs, I'm afraid that's not the case.
There are countless differences between pianists of different skill levels but the fact that these differences exist is not an insult. As another example, many students who have only studied for a few years will learn many of their pieces hands separately before putting the hands together. Once pianists reach a more advanced level they don't normally do this. They might practice only the most difficult passages hands separately. I have recently been learning some song transcriptions by Stephen Hough. Although I would consider myself quite advanced for an amateur, I know I will never be able to play these nearly as well as he can(and many of his song transcriptions are beyond my ability to learn at all), and he may well have just played them through a couple of times before recording them whereas I have been spending many weeks on them.
Differences in skill, thinking, learning, approach, etc. are there whether the activity is playing the piano, tennis, chess, math or any other activity. There is no imaginary threshold between beginner, intermediate, advanced, etc. The level of skill in any activity is a continuum.