I have dealt with 1 modern-ish/heavy car that stalled its engine on a downhill slope and my braking ability in this case was reduced to a mere suggestion. If you are strong enough to bring down an unpowered 4000lb+ vehicle to a complete stop on a downslope, more power to you but it is a bit unfeeling to assume that everyone shares your extraordinary pedal-pounding strength. Edit:s/freakish/extraordinary.

4,000lb Toyota LandCruiser with drum brakes and no vacuum “power assist” enough of a test?

You have a tiny master cylinder compared to a vehicle with power brakes, so it should work fine... this is different than having a big master cylinder + power brakes disabled.

Did you even read the PDF? "holding against WOT requires average of 175 pounds of force on brake pedal"

Yes it was an option, with an appropriately sized master cylinder so you didn't have to push as hard.