I think this idea seems reasonable, and given the explanation I fully agree that this is not a dupe and enough time has passed that a new discussion about this idea is justified.
I have a few concerns, though. My major general concern is the possibility that this will unnecessarily increase the amount of meta complaints from users wondering why their edits were rejected, to no real end. I have no concrete evidence to back that up, it is only conjecture. Still, I am traumatized by the number of complaints that stem from negative feedback in general ("my post was downvoted", "my post was closed", etc.) and have similar concerns here. In general, there seems to be a policy of not giving notifications of negative events, and for good reason.
In any case, breaking down some of the points individually:
- Users already receive notifications for accepted edits via the +2 rep gain
Tied in to some of the concerns mentioned above, the existence of a positive notification does not justify the existence of the corresponding negative one (in the same way that the existence of answer notifications is not a rationale for adding closure notifications).
(PS, fwiw, that +2 gain stops after you've gained 1000 points through edits, or you've obtained the edit privilege.)
- The current edit warning doesn't immediately specify which edits were rejected
There is a link to the recent edits, where you can review. If multiple edits were rejected this gives an opportunity to look at all of them. Still, fully support the notion of making it clearer. Personally, I think a list of recently rejected edits directly in the warning could be useful. On the other hand, that does only save one click.
- It's unclear whether the rejected edit warning is being shown for a recent rejection, or an old rejection you already knew about
This seems like a solid point. There is no way for the system to know if you already know about a rejected edit, and a notification would solve that.
On the other hand, I'm not sure if it necessarily matters. If you receive this warning, you need to become a better editor. If, when reviewing your list of recent edits, you happen to re-look at a rejected edit you already knew about, this doesn't really hurt anything aside from wasting a small amount of your time, but then again, if you start making better edits, you won't have to spend time reviewing rejected ones any more. This is a weak "on the other hand", though. I do think that if there are any compelling reasons to have a notification, your bullet point here plus your last point (below) would be those reasons.
- You only see the warning the next time you suggest an edit, which could be days or even weeks later
This isn't so much a point for the notification as it is a point for keeping the warning (regardless of a notification). See, the purpose of the warning is to let you know that you need to improve your editing. On the extreme, if you never make another edit again then it doesn't matter. More generally, it does not matter if you improve your edit skills until you actually make another edit. You want to see an old warning right as you are about to make a new edit. This is the most important time to let you know you need improvement: When you're about to take an action.
If the choices are:
- Rejected edit → warning → a few weeks pass → edit something, vs.
- Rejected edit → a few weeks pass → warning → edit something
I'd rather users go through flow #2, so that their previous mistakes are fresh in their mind when they're about to potentially make another mistake, instead of giving them a long period of time to forget the feedback.
So if there were to be a notification, the warning really ought to stay as well.
- The rejected edit warning is site-specific, meaning it doesn't display when visiting any of the nearly 100 other SE communities.
This is a great reason for a notification. To be honest I'd rather see the warning be global but I have a hunch that isn't exactly feasible to implement, and a notification would help out here.
I suppose you could make a counter argument here that editing policies may vary by site and so "global" is not appropriate, but I think that doesn't matter, since this is feedback on what not to do rather than on what you should do, and so any improvements to your editing skills in this regard will likely benefit you on every site.
That said there's a bit of a bigger picture thing to consider here which also keeps me on the fence: Does this matter?
I mean, what are the downsides to continuing to not have a notification? See:
- Users who are serious about their edits and motivated to contribute positive changes, or motivated to improve, won't have much issue reviewing their rejected edits on their own. And even if they don't take initiative and only react to warnings, the reasons for rejection are a small enough set that even if they miss a few of their rejected edits when reviewing their rejections, there's still quite a lot of opportunity to learn.
- Users who improve naturally on their own over time, well, all these warnings and notifications are moot for them.
- On the other hand, to be blunt, users who can't improve without the notification will either end up edit banned or just stop editing, and this doesn't hurt us. These people aren't contributing anything particularly critical to site quality.
So: TL;DR: Totally on the fence, but:
- Notification or not, the warning should also stay.
- Out of your points, the following two seem the most compelling, and the rest do not:
- "It's unclear whether the rejected edit warning is being shown for a recent rejection, or an old rejection you already knew about."
- "The rejected edit warning is site-specific, meaning it doesn't display when visiting any of the nearly 100 other SE communities."
- I still wonder if this matters in the grand scheme of things.
- The possibility (again, though, conjecture) of increased meta complaints about rejected edits kind of offsets what appears to be marginal gains. I could probably be convinced if a better argument about concrete positive end effects was given.