There are rumors that it's due to the fact that it uses Denuvo. This is used to prevent the game from being pirated if I understand it correctly, but it causes other issues like worse performance and prevention of modding.
Don't quote me on that though...
On the Official inZOI Discord FAQ channel it states:
Question: Can we use mods?
Yes! inZOI has built modding using Unreal Blueprints (changed from the previous Lua iteration).
The inZOI team will provide modding guides and tools for easier implementation.
Taking a look at Unreal Blueprints it states:
The Blueprint Visual Scripting system in Unreal Engine is a complete gameplay scripting system ...
So that's looking good for gameplay mods in my opinion. Granted, I'm sure they could restrict what's allowed with Blueprints, but I like to stay positive!
