The other way might be testing VMs vs agent VMs but that would be slower as to "fork" it would need to run the test again to that point. But wouldn't need agent context.
That + its not always simple to replicate state. A QA agent in the future could run for hours to trigger an edge case that if all actions to get there were theoretically taken again it wouldn't happen.
That can happen via race conditions, edge states, external service bugs.
The forking you provided adds a lot more speed.