That last sentence pretty much gets it perfectly

I think slings are treated similarly to throwing by the brain, which humans do very well

A basic sling should be very consistent and simple. Early bows have a lot of advantages but the mechanical complexity makes them less consistent. 50cm of rope is 50cm of rope, it’s gonna throw the same every time as long as you’re practiced. Bows are made of natural wood and fibre with all kinds of tensions and inconsistencies, as well as requiring more work to repeat the same action precisely

POV became MFW at some point