On extremely technical trails you can't even ride in first. You have to slip the clutch to get going. Well slipping the clutch dumps tremendous heat into the clutch plates. Do it too much and they literally burn. On a cable clutch the free play increases as the plates swell from the heat. On my bike I will smell it as the vapors get out the crankcase breather. If you keep it up it only takes a little more and you destroy the fiber plates. Then you are stuck with no connection between the engine and the transmission.
I've never got stuck from it because I notice the signs and stop so the engine can cool.
Hydraulic clutches mask the plate swelling free play increase.