I asked this nearly 8 years ago. In that time, the function in question has been split into separate blender and compositor tools for sake of maintenance, but the main user-facing tool still carries the synopsis for everything, amounting to a bit over 700 lines. Core usage information is up front, then a long table, and then descriptive details for specific modes and families of modes. It's a lot, but it's fairly compartmentalized. Still, it always bothered me that this is the price of trying to be comprehensive.
Today, I opened PsychImaging() from PTB -- a editor-lagging 5k line file with a synopsis nearly 1700 lines long. I don't really feel so bad now.