When you call the humans who keep production safe “the bottleneck” you’re painting a very specific picture. The reviewer as the obstacle. The gate as friction. Something to route around. Cue in the Balrog scene from Lord of the Rings. That picture determines what you build. The tools to remove reviewers look different from tools to support them.
No, the bottleneck is not always requirements. Understanding requirements is a prerequisite to writing correct code, but it takes a fraction of the time.
Obviously different domains have different complexities of requirements and code which changes the ratio