It's a near certitude that Russia and China each have databases of exploitable software errors and prize zero days.

It was to the advantage of the US and allies to coordinate and lead in tracking and fixing such errors.

Multiple countries, companies, and individuals contributed finding and fixing bugs.

The administrative task of keeping track was one part of a greater picture, a part that came with first to be advised and other perks.

It's not that the US had a responsibility to take on the lead admin task, more that in past times the US saw an advantage to being at the centre of global action.

This is just another part of increasing US isolationism.