I think the reasoning is that the world is built for humans, so if you need a robot to do arbitrary human tasks in an unmodified environment then perhaps that gives an advantage.

The premise itself seems bogus though - there's plenty of tasks such as traditional assembly line and conveyor belt automation where a stable robot bolted to the floor, with a wired power source and custom manipulators is going to be a much better option.

For a mobile robot stability and reliability are key, and it's hard to see how a humanoid robot would be anything other than a massive downgrade for applications like Amazon's warehouse robots, hospital drug delivery robots, mall security robots, robot vacuum cleaners, etc. Wheels for the win.

OTOH there's the dream/hype of a domestic robot doing all your household chores, where humanoid form might actually be a plus, but at this point that's a pipe dream, and I seriously doubt many people really want C-3PO in the kitchen washing the dishes even if he is managing to do it without breaking anything or short-circuiting himself. It's like a 60's vision of the future, with people in flying cars or living on mars. No product-market fit.