There is possibly a misunderstanding on your part regarding "being moved by art without knowledge of the artist". In my case, the comment was specifically addressing this assertion by OP:

"We associate Van Gogh's art with his madness, Da Vinci's art with his universal genius, Michelangelo's art with his faith, Rembrandt's art with his empathy, Picasso's art with his willingness to break with norms, and Giger's art with his terrifying nightmares."

Disagreeing with this is not about internal or external semantics. It also does not imply that "aesthetics" alone create a mental state. Great art is typically rich in symbolism as well. Symbolism that directly references humanity's aspirations, hopes, fears, dreams: the Human condition.

A ~contemporary example:

The Bride Stripped Bare by her Bachelors

https://i.pinimg.com/originals/86/0a/6d/860a6d3c87b349734277...

In my opinion, you don't need to know anything about Duchamp to decipher (or project as you wish) meaning here.