Jeep GC creeps in neutral

My Jeep GC 2001 creeps in neutral. However, it won't accelerate when hitting the gas pedal, which means that the clutch is indeed disengaged. This seems not normal but some guys found this phenomenon and explained that the tranny gears would still rotate by the fluid turbulence which is propelled by the engine output shaft.

Moreover, it is quite interesting that one Jeep guy was very much proud of the ability of Jeep GC that it could "idle in neutral and crawl up an incline at 10,000 feet in the mountains", which is exactly the phenomenon I am worried about!