How to understand " imitation is the bottleneck of culture" can it mean "it is crucial to the very existence of culture"?
I agree with colloquium.
"Bottleneck", in scientific terms, means the "rate-limiting" step.
"Nothing can flow out of a bottle faster than it can flow out of the neck of the bottle" is the exact meaning.
If two lanes of traffic merge into one lane, you might get a (metaphorical) "bottleneck" there.
Concerning culture, if everybody imitated someone else, there would be no true innovation. All art, for example, would need to pass through the bottleneck of imitation.