I was on a Delta flight from HKG-NRT-HNL (my segment that I was going to take was just HKG-NRT) and the "no liquid for flights to US rule" was applied.

Those liquid check is not those bullet proof as those in US airports. They just open up your bag and see if they can spot any liquid. I was able to carry my water bottle buried deep down in my backpack though this.

As the plane has an enroute stop at NRT - why this US rule applies? I can carry as much liquid I want if I get them at NRT post security.

And they have done it so badly - I saw several people successfully carried liquid though this, and those liquid is from clean zone at HKIA.

This is the dumbest thing done by HKIA management I have ever seen.