Thinking about buying a 5.7 Dodge half ton truck.

Towing capacity is just that, you can put a 4 down 10,000# vehicle connected to the rear of the truck and tow it. The number isn't a fallacy, it's simply misunderstood.

A travel trailer or fifth wheel is towed AND carried, so both towing capacity and payload have to be considered.

If someone would make TT's that are on 4 wheels, 1/2ton trucks would be able to tow a whole lotta living space.