Eric, have you ever drilled cast iron? Its very soft. I drilled the upper arm of my cast iron frame bandsaw to install the Carter Quick Tensioner. Drills like butter. Have you ever drilled steel? Much harder to drill. When I assembled my Griz G0457 I looked up into the spine and if I remember correctly, its 2 square channels of steel. Steel framed saws can tension a blade to a much higher level, which is needed for better resaw results. Have you ever seen wheels for a car made from cast iron? How about bearings? Clamps? Any time higher strength is needed, steel is used instead of cast iron.
My favorite cologne is BLO