I actually didn’t ask them but this is why they don’t allow mods.
Apple won’t allow mods because of their policy on third party executable codes. Pretty simple right?
If you’re a stubborn person you may ask why they have this in place.
Short answer: iCloud
iCloud works by uploading and downloading files as a sort of backup protection so your iPhone can get images of of your computer and vice versa. And your phone is in constant contact with iCloud when you have internet
The reason why executable files (mods) aren’t allowed is because your iPhone may run a mod and that mod may contain a virus and when your iPhone contacts apple that virus can travel to an apple server (hidden as an image or something) when the file reaches the servers BOOM 1 billion+ people’s data is compromised
There you go