What is the real purpose of the Camera distance?
At position 0 the scene disappears.

At pos.1 something appears.

At pos 2 the scene is back.

At any other position up to max. there is no change noticeable in the scene.

It determines the distance that the camera clips the scene. Say you want to build a really massive world, the default camera will clip the end of it. so now you can increase the default. try flying really far away to see the effect, or place a mountain piece and scale it really big