I'm not convinced. Flexing the sides requires negative curvature or non-convexity. Triangles are easy to draw because they have fewer sides than a square, thus

I'm not convinced. Flexing the sides requires negative curvature or non-convexity. Triangles are easy to draw because they have fewer sides than a square, thus positive curvature makes it possible to create a 3-right triangle. Octagons are the opposite.