This still sort of codifies the edit is a discrete event, and not an ongoing process.

That's a good thing, because that final edit is a discrete event. At some point this ongoing process will end and the edits will stop. The people engaged in the process will likely forget or not be available to add a final timestamp, but an aging edit timestamp will automatically indicate this moment in time.

It is always and ongoing process until it isn't. Knowing if/when the transition happened is useful.