The difference is that you can, and could, make fully functional physics-based games in Unity and Unreal because their in-house engines were accurate and perfor

The difference is that you can, and could, make fully functional physics-based games in Unity and Unreal because their in-house engines were accurate and performant enough. The point of integrating Bullet/physX was to provide the option for even more accurate physics engines. Godot's in-house engine is neither performant, nor accurate, and it boggles the mind to think that having abandoned the relatively easy task of implementing a single physics engine written in the same language as their game engine (and that their competitors were able to integrate and support) that they would be able to accomplish the far more difficult task of implementing an engine-agnostic interface supporting multiple physics engines, as accomplishing the latter would require them to first accomplish the former...