Measured every minifig leg type with calipers, long legs come out exactly 8mm taller than standard and I can't figure out why

Got nerd-sniped by my own collection this week. I always figured a minifig was basically three parts (legs, torso, head), but pull one apart properly and it's nine: hips, two legs, body, two arms, two hands, head. So I got the digital calipers out and measured a standard minifig against a LEGO Friends minidoll to see what actually changes between the two systems. The minidoll comes out 4.7mm taller to the top of the head stud, but drops to just five parts total, way less mix and match. While...