Since there's a lot of people who clearly haven't read the editing guide, I'll post this relevant quote (emphasis mine):
It holds all the official specifications given by the developer on what is required at the minimum to both run the game at a basic level and run it with all graphical settings maxed out at a playable frame rate.
As such, unless the recommended settings can be proven to meet that last statement, that's why the 4K Ultra settings have been used. They're the highest requirements on the list and, as such, the ones which logically would allow the game to be run "with all graphical settings maxed out at a playable frame rate".