This is such a weird counter-argument, that only serves to prove OP’s point.

“It’s not that it’s not documentable. It’s just that it would take tens of thousands of pages and no one would be able to write that or read that to effectively take over the project.”

Okay, so surely this is what OP had in mind when they said documentation doesn’t work… Is it no longer safe to assume reasonable expectations when making an argument? Why the need to “well actually” them with this response?