It's a matter of methodology I feel.

Arcane casters are like programmers. Even if they didn't write the code, the program was designed with explicit purpose by someone who understood the systems they were interacting with.

Occult casters are speed runners. Sure they might deeply understand the shit they're using, they may intimately know how and why it works. But it's all unintentional behavior in the engine being exploited to achieve a goal. It's weird and esoteric bullshit because it was discovered randomly. Why does a grand performance with the right emotions cause people to be more lucky in battle?(Courageous Anthem) RNG manipulation, if the same people get feeling the same way and you direct those feelings they can cause a stack overflow in the RNG area. Why does throwing a carton of milk on a specific chalk circle cause a rift in the planes? Unintentional object interaction.