A number of the examples do scene.add(camera), but a number of them don't. What's the use case for doing so?
The camera will be added automatically if you don´t add it to the scene. I believe when you´re using only one camera it´s ok but if you´re using more then one you should at them.
Until recently the camera wasn't part of the scene graph. Because of that most of the example never add it to the scene so we do that automatically if the camera has no parent. Now a camera can be part of the scene graph, meaning that can be a child of an object. Imagine having a car on your scene and you want to put a camera on it.
Since not adding a camera to the scene is deprecated shouldn't all of the examples add the camera regardless?
They already do:
I'd just like to note that the README's copy+paste example does not add the camera to the scene. It only caused me a minute of confusion, but it might be a good idea to fix it.
@egpaik As of r.50, the camera no longer needs to be added to the scene.