Genuinely curious, did we ever manage to ban a piece of technology worldwide and effectively?
A large part of geopolitics is concerned with limiting the spread of weapons of mass destruction worldwide and to the greatest possible degree of efficacy. Moreover, the investment to train state-of-the-art models is greater than the Manhattan project and involves larger and more complex supply chains-- it cannot be done clandestinely. Because the scope of the project is large and resource-intensive there are not many bodies that would have to cooperate in order to place impassable obstacles on the path that is presently being taken. 'What if they won't cooperate toward this goal?' -- Worth considering, but the fact is that they can and are choosing not to. If the choice is there it is not an inevitability but a decision.
Do chlorofluorocarbons (CFCs) mostly banned by the Montreal Protocol count?