The problem is, that making a 3D engine is extremely tough, and most 3D engines are completely proprietary as a result. There are plenty of 3D libraries that ma

The problem is, that making a 3D engine is extremely tough, and most 3D engines are completely proprietary as a result. There are plenty of 3D libraries that make 3D game development for small games easy, but when you compare a Python library next to a system that includes a 3D engine, a level editor, a file management system, and the ability to easily compile for different systems, its no contest for game companies. A fully-fledged development environment scales better for these multi-million dollar projects than a singular library. It's why in the 90s every game was mostly built on an engine specifically designed for that game, and in the 2000s they switched to prebuilt game engines. Saves a lot of time AND money.