Or to classical organists, one of the few classical specialties that has preserved improvisation as a major part of their skillset. (In the times that classical music was composed, musicians were encouraged/expected to be able to improvise. E.g baroque & classical period concertos where the cadenza was essentially an empty space in the sheet music that meant "improvise here". Some of Handel's organ concertos have no second movement written down because he would just improvise.)

Not sure whether parent is deliberately trolling but literally, the first two words of the article are Keith Jarrett. The statement describes how it applies to his music.