I'm not looking at it like a line by line explanation of the code. Think of it like commit messages, but better. Better because:
1. commit messages are usually not very informative and the context is implicit.
2. commit messages are coupled to time rather than to the final PR changes. The PR changes are what really matters to the reviewer, not a log of what the author did to get there (especially if things are changing back and forth).
I'm not looking at it like a line by line explanation of the code. Think of it like commit messages, but better. Better because:
1. commit messages are usually not very informative and the context is implicit.
2. commit messages are coupled to time rather than to the final PR changes. The PR changes are what really matters to the reviewer, not a log of what the author did to get there (especially if things are changing back and forth).