When you look at the piano from above it IS a harp laid on its side. I never realized that until looking down on the stage at Orchestra Hall one evening.
Wonder why D never wrote any piano concertos (at least any part of the common repertoire) or symphonies.
I don’t think it’s a huge deal that Debussy didn’t write symphonies or concertos, because he did write 4 ballets, numerous orchestral works, numerous compositions for voice and orchestra (such as “Printemps”), for instrument (such as clarinet, piano, harp) and orchestra, numerous solo piano works, chamber music (such as “Danses sacrée et profane”), piano works for 4 hands or 2 pianos, works for voice and piano, and works for a cappella voice. Maybe he just didn’t like the symphonic and concerto forms and prefered more non-structured forms.