Aren't you forgetting about the keel/center board? The keel only produces lift when in motion, thus it is very important, as you can only start sailing upwind o

Aren't you forgetting about the keel/center board? The keel only produces lift when in motion, thus it is very important, as you can only start sailing upwind once you have a bit of speed. It's not the projection of sail force in direction of the boat that causes forward motion, but the addition of sail and keel forces.