I'm thinking of when I'm trying to get over an obstacle, or up a hill when I have very little traction and I'm only using a tiny amount of throttle. The wheel doesn't spin very fast, but loses traction immediately. In this case, where the wheelspin, to me at least, doesn't seem like it would be fast enough for the bike to know I'm not actually moving, how would it know you don't have traction. It's easy to identify wheel spin speeds that are much faster than realistic acceleration would allow, but when stuck on a hard trail or obstacle, you are at wheel speeds that are considerably slower. In this range how does the bike know it loses traction? In this instance the wheel spin would be limited to what the bike "thinks" is an acceptable rate of acceleration, but in reality it has no idea what the bikes actual acceleration is. An onboard accelerometer, like in our phones would work too. All I'm saying is that monitoring and limiting wheel spin acceleration is a very crude version of traction control, it's not true traction control. The theoretical limit of wheel spin acceleration for a bike with racing tires on a street track after they've been warmed up is completely different than a dirt bike with worn knobbys on a hill in deep, slick mud.