Why Would Anyone Want to Learn Chords Or Chord Progressions?

There's a famous story about a world-class concert pianist who when asked to play "Happy Birthday" at a friends' home couldn't do it because there was no sheet music available for it in that home. That's an extreme and pathetic example, but many lesser embarrassments happen every day around the world because piano players don't know theory and don't understand how chords tie everything together.

Georges Braque Pieter Bruegel Edward Burne-jones Alexander Calder Adolphe Cassandre