> In every prize I’ve ever judged or heard firsthand reports of, everything else is up to the judges and their idiosyncrasies.

Sure. But even seemingly broad guidelines deeply influence/constrain the judges' choices.

E.g., the Pulitzer was created when America was still insecure about its artistic output and stature compared to Europe. Judges of the music prize were consequently asked to choose from "music in its larger forms," meaning ambitious, large-scale symphonic or chamber works typically derived from conventional European forms/genres.

The problem is that 20th-century American musical innovation almost definitionally meant straying from those conventions. The most banal example: Conlon Nancarrow's complex tempo canons that required hand-punching rolls for the player piano. There's a hard limit to the thickness of a piano roll that necessarily limits the duration of any given piece.

Composers began making pilgrimages to Nancarrow's apartment in the 1970s just to hear his music. By 1982, he'd won the MacArthur Fellowship for his Player Piano Studies. Funny enough, that same year, octogenarian composer Roger Sessions-- a former teacher of Nancarrow-- won the Pulitzer. His piece? A concerto for orchestra.