I have a conspiracy theory here, they always forecast higher for China expecting lower and they forecast lower for the US expecting higher. So investor feel more confident putting their money here and no elsewhere. "Look the grass is always greener over here".
either way is a weird situation for the FED.
I would believe it is a more basic propaganda strategy.
What is China's strength is its people, like what Chairman Mao believed, the masses. This translates today into economies of scale, fueling the economic juggernaut, that fuels everything else from military to technology to diplomacy.
The United States has to be just as big or bigger, and they would need allies to take on China, the United States cannot do it alone.
Therein lies the problem, because no one like losers. If the United States appears to be weak or losing, their allies will not be happy and could be thinking about themselves.
So the propaganda campaign is to keep the allies together on the same page in regards to China.
Does not matter if no one else in the world believes it, as long as US allies believe it, the west, then this outlandish propaganda is worth it.