"Granted, the composer wrote all those notes and gave them all purpose. But there comes a time in music when the notes are only a guideline. Mistakes? More like deviations from the composer's outline, intended or not. As others have said, a mistake is only insomuch as the performer destroys the atmosphere and musical experience that he has created for his listeners. A wrong note here and there? Pshaw. The only reason we've come to expect note-perfect performances is because of digitally edited recordings that seem to set the standard for live performances as well. The pianists themselves understand this, but sometimes not always the listeners."
Thank you for your very well thought-out analysis. You have attained an analytical mindset/epistemology that most pianists never attain.
Accordingly, this was explained to me in the early 1980's by the classically degreed jazz new world pianist Hank Hemsoth (student of John Perry of UT Austin, BM & MM). If you have viewed the Film/Movie "Arthur," that is him!
Therefore, as a composer/jazz pianist (who has actually written/composed music most of his entire life), he schooled me on the epistemology of music composition. That means when a composer first conceptualizes a work, they hear it in their head. They do not see staves, bar lines, and notes on a page. The final published score is (and has been for centuries) a very rough approximation of the "sound" the composer originally intended.
As a philosopher scientific empiricist myself, this prior statement does not denote or connote the work of Louis Podesta. It is instead (citing other sources) the published mindsets of Dr. Clive Brown of the University of Leeds
https://music.leeds.ac.uk/people/clive-brown/, and also Dr. Neal Peres Da Costa of the Sydney Conservatorium
https://sydney.edu.au/music/staff-profiles/neal.peresdacosta.phpConversely, my coach just recently said to me: "John Perry said this, and then Leon Fleisher said the same: " if you want to know how to play Beethoven, then there it is on the Henle Urtext version printed page right in front of you."
Are these two individuals famous? Yes, they are. However, they do not have any credentials whatsoever which would have resulted in them publishing in their entire lifetime one single Journal artice to support their thesis. It is, per the OP's original question, what many of us know as the Music Conservatory, Big Music School propaganda,
In his Memoir, the late Earl Wild, stated that this "Urtext" nonsense performance practice did not exist before the end of World War II. He quotes the late Jorge Bolet as referring to the "Urtext Mob." Further, the Curator at the UT Austin Fine Arts library recently stated to me unequivocally that the world musicology community no longer considers Urtext scores as legitimate.
Heinrich Schenker invented Urtext to clarify that the improvisers of his day had every right to put their own spin on Beethoven's works, but they did not have the right to go out and publish these improvisations as the proper way to play his music. Beethoven was the most famous improviser in all of Vienna, but the fact remains that he never played any piece the same way twice.
Finally, when interviewed by Joseph Horowitz regarding one of his recordings, the late Miecyslaw Horszowski (student of T. Leschetizky) stated that one of the main differences between 19th and 20th century performance practice is that back then nobody got bent out of shape if someone missed or played a wrong note.
Enough said!