> One question you asked in there was how was being able to "unwrap" a start
> into a Process key given the Process creator useful. The big use is
Another common use is in the "destroy" logic. When a process wishes to go away, it must somehow destroy itself. It does this by returning to the process creator. The process creator holds the brand of the process, and can therefore obtain the process capability for the dying process by converting from the resume capability in order to tear it down.
Note that this is purely an efficiency. The process creator could, in principle, have simply kept a list of process capabilities for every process it ever created.