That’s because it’s easier.
Most games do not even have official modding support, Minecraft included. Most are only moddable because they use some interpreted programming language somewhere in their game, which people found ways to read and inject with their own code.
Yep, did this, looked great and I loved it. Botw modded was a great experience. Just skipping all those unskippable cutscenes was worth it already. (Teleport animations, sign repair dialogue, etc etc)