Hmmmm.
As the guilty party who initiated this line of discussion, after reading the posted responses I have to admit to having some second thoughts. I was particularly taken aback at the quoted examples of ego-driven back-biting, in response to input that was no doubt intended as helpful constructive criticism. I also see examples of the dangers of social media participation in some cases, where a photographer's self-image about their work can be built up to a point of being (to them) beyond criticism. I do wonder what percentage of photographers are inclined to react in these ways (hopefully low), but it can be very disruptive and upsetting when it occurs. Because of these sources of risk, I concur with Graham about the potentially large requirement for moderation associated with an introduction of Comments on submitted images.
Another point I was unaware of until it became clear in this discussion, is the frequency with which Moderators contact submitters of new images to bring attention to the need to correct faults before image acceptance. I thought that this was pretty rare, but it seems perhaps not. I recall being the recipient of such feedback at time of submission on a few occasions, including one from Graham Cam to do with the techniques involved in correcting red channel blowout affecting part of my image - the very helpful advice resulting in a vastly improved image. In that case, as well as an acknowledgement for the help, I was careful to include a brief explanation of the fix in Comments with the image so that others could learn from the feedback. It would be good if anyone receiving help in this 'hidden' way used the Comments field to do likewise.
I think it should be the right of Moderators to contact submitters of new images in regard to image problems. It would also be good to know that other experienced members continue to feel free to send image advice to other members, using the Contact Photographer button - but how to avoid the sort of issue that Ian encountered? The only thing I can think of is for the intending advice provider to first send a message asking whether the recipient wants feedback - maybe this could be automated in some way?
Anyway, it will be interesting to know what the Committee think. I apologise in advance for inadvertently re-opening a rather complex can of worms that they may have preferred remained closed!
Cheers, David