Helps the maintainer focus their efforts during review. If you wrote that exact sentence, a maintainer would keep "understanding of the codebase" as a place for potential sources of incorrect assumptions higher in mind than otherwise.

In my experience, if there's one thing the AI assistants do really well, it's understanding existing code and summarizing it or pinpointing specific things I'm looking for.

I'm not really a developer but I routinely need to go dig through codebases looking for answers and AI assistants have made this so much faster. This has been a boon for me.