Ok, I am most certainly NOT a knowlegaeble person but I'll give it a shot...I'm thinking a worn clutch dragging as opposed to slipping
is kinda like a torque converter in a car. I mean the oil in the clutch pack may be locking it up. The serrations on the clutch plates on a wet clutch " fling" the oil out of the pack allowing it to lock up. If the serrations are worn off the oil clings to the plates and locks the plates up even with the clutch lever pulled in. Again, kinda like a torque converter. I'm sure I'm totally wrong on this but I gave it a shot! lol.
Wayne