Scapple doesn't force you to make connections, and it doesn't expect you to start out with one central idea off of which everything else is branched. There's no built-in hierarchy at all, in fact--in Scapple, every note is equal, so you can connect them however you like. The idea behind Scapple is simple: when you are roughing out ideas, you need complete freedom to experiment with how those ideas best fit together.
Creating notes is as easy as double-clicking anywhere on the canvas and then typing; making connections between ideas is as painless as dragging and dropping one note onto another. And unlike with paper, you can move notes around and never run out of space.