I agree that code reviews should be important, and key to understanding the history of a project at a more useful timescale. I just disagree that they should be "atomic" and that a reviewer (even, or especially, a later code archeologist) may not have reason to inspect or dive into smaller units within code reviews.

Where I think that we may agree is that I feel that even if they shouldn't necessarily be "atomic", I agree that code reviews should probably be first-class objects when talking about and dealing with source control. In git, you can use --no-ff merges today as a useful approximation of code review boundaries (especially with PRs and GitHub's default --no-ff and including linking PR #s). It might be nice to see code reviews or other aggregates of commits/commit graphs be truly first-class citizens of git in some manner.