Correct me if I'm wrong, but isn't one of the main reasons for not using a game engine to make GUI applications, how the game engine uses a lot more resources. One example is how a typical GUI application will just update what has changed, but a game engine will run full screen updates and a lot of them.

Very interresting read. It seems that the majority of the mentioned cons is something thats going to be fixed. And then Godot might truly compete with other app development frameworks