It's a good question! Having a history of how things transformed over time matters. We keep track of that in a couple of ways - one is the graph snapshots themselves, and the other is a raw history log. It's really just another view of a snapshot of the graph at a particular time, and a delta between that graph and the current.

We have lots of planned work coming here - but we have a very rich dataset to do it from, and we're stoked to get there.