I don't agree. For example could Shostakovich's symphonies be composed in a world without WW2 and Stalin? They were major factors influencing what people value in an artistic experience, as well as influencing the composer directly.

Bach composed for the religious people, Mozart for nobility / people who could go to the opera, Beethoven for the romantic middle class who owned a piano, and Shostakovich for the oppressed masses in soviet Russia. The historical context shapes artistic criteria.

You can't make new art styles in a vat (brain in a vat), the process is connected to the world.

The fact that we can say a person revolutionized the field is specifically because their work, at some point in time, got recognized by a larger audience. The fact that an artist had pushback is also context that is used to determine something is revolutionary; you cannot have subversive art if there is nothing to subvert.