Because as the stories derived from the Snowden leaks show, nation-states hold vast troves of exploits and tricks up their sleeves to break and bypass security.

Because as the stories derived from the Snowden leaks show, nation-states hold vast troves of exploits and tricks up their sleeves to break and bypass security. Imagine a card game with the object of getting the best hand. Three communal cards are placed on a table face up. China and U.S. each hold their own cards which they don't show each other. Now imagine that China, the U.S., and a set of international researchers acting in good faith all interact to decide which communal cards are placed on the table face up. The researchers can give whatever constraints they want-- maybe they want all face cards, or all the same number or suit. The U.S. and China can "play along" while at the same time making choices within that set of the researcher's constraints to maximize the chance that they have the winning hand. U.S. and China can even guide the researchers away from one set of constraints to a different set if it improves their odds of winning. So if U.S. gets to guide the constraints exclusively they greatly increase their chances of winning.