I can have a go at restating George’s requirement, and I suspect provide an answer… of sorts…
You have a RAW file, freshly opened in PL. You spend 10 minutes mucking around with the sliders until it seems just about right. You export the result as a JPEG and then have to go away and do something else for a while.
Later you return and look at the exported image and decide, on reflection, that it’s not what you wanted. So you spend another 10 minutes fiddling with sliders but in the end it looks worse! If only you could go back to how you had it when you first exported and try again to tweak it.
There’s no simple way to get back to that point unless you had the forethought to make a virtual copy before doing the second round of tweaking. Even using the undo action, you’d likely be guessing at the point to return to because you’ve just spent 10 minutes fiddling with sliders and some of them more than once.
So what George is asking for, I believe, is an option to revert to that previous point (at which it was first exported). The trouble is how to define that point? It might be “the point at which I selected this photo in the editor” or “the point at which it was last exported.” Anything where the user must take a conscious action can be covered by virtual copies, but this requires forethought that you’re going to muck it up.
The answer, perhaps, is to get into the habit of creating a virtual copy immediately prior to exporting. This would work in the latter case suggested, or in the former, get into the habit of creating a virtual copy of any photo immediately prior to doing any editing. This seems cumbersome either way. What is trying to be achieved here is some kind of “editing session” which can be undone in whole without having to manually define that session.
A new software feature would automatically mark one or both of these actions in the undo buffer and allow you to see them in a history list, allowing you to select the ‘rollback point’ and undo to there in one go. Plus, with a visible edit history and rollback to any arbitrary point within it, there would be less need to use virtual copies as ‘protection,’ leaving them for their (I believe) intended purpose of applying multiple treatments to the same image deliberately.