I m a bit surprised by TFA: most C64 games, by very far, would also run entirely in memory. Some would load mid-game or even use several disks (like Ultima) but these were the exception.
"However the Apple II disk drive is very fast, so unlike the Commodore 64, single-load games went away quickly. C64 games did a lot of work to stay single-load since the C64 drive is so slow, but on the Apple II, running back to the disk to load your title screen, menu system, or new levels was no big deal."