Ah yeah, connecting the dots in ggplot2 docs is hard. It's hard for us to document because, under the hood, the pieces quite decoupled and different pieces are responsible for different arguments. But since we last took a deep dive on the ggplot2 docs, we've gotten much better at generating docs with code, so maybe it's time to have another look. I've filed an issue (https://github.com/tidyverse/ggplot2/issues/4770) so we don't forget about it, but no guarantees about when it might get done.