Why does ProRes have to use ExFAT?

According to Apple's documentation, to record ProRes video:

Your external storage device must be formatted with exFAT. Password-encrypted drives aren't supported.

Apple always promotes their own file system, APFS. I've been using it for years and I think APFS is good. ExFAT is described as "not safe" because it lacks a journaling system and is prone to corruption.

Then why doesn't Apple use APFS?