It's like someone who says "Who are you to judge art? Arrogant much?" But then in a photo thread they say "Yeah, this is a snapshot." People don't want to associate with the negativity because they're afraid it will hurt their social capital, but then in certain situations they feel justified giving similar negative feedback because "It's different in this instance."
I understand what you are saying, but I don't feel it is hypocritical to offer feedback while at the same time believing the future value of a piece is largely unknowable. That has been the condition of pretty much every mentor in the history of art, including the greats, like Da Vinci. His mentor sent him to the royal court as a musician, not a painter. But music probably had an interesting influence on his work, so who knows.
Pretty much throughout the history of art, there has been "mentorship." A less experienced artist under the guidance of a more experienced one. I see this forum as acting in that role to some extent, although it can also be a bit of the blind leading the blind. But there are different levels of experience here, and we can make some judgements based on what has worked and not worked in the past. A "snapshot" for example, can absolutely work as "art". There are plenty of examples where it has worked, and some photographers have intentionally used the snapshot as a stylistic choice.
I think critique starts to fail when one judges every image by a very narrow set of standards intended for a specific genre. It would be like judging the Eastern Canon by the Western Canon's standards. For hundreds of years, that is exactly what happened. Non western art was thought of as primitive and without value because it didn't conform to the standards of the Western canon. In the 60's, that all started to break down and any art critic worth listening to will adjust and adapt their criteria based on what they are looking at and its context.
So, I think the biggest problem in critique is judging an image on a set of standards that are irrelevant. To judge every portrait based on the standards of commercial portraiture is a mistake, or every landscape on the standards of Ansel Adams, or every travel photograph on the standard of National Geographic, or even judgements based on personal likes and dislikes--hyperrealism, extent of processing, too dark, limited tonal ranges, unhappy subjects, unconventional color palettes, etc.
Fortunately, I think we have a lot of very knowledgeable and experienced participants on this forum. Not to put anyone on the spot, but Derrel is really good at using standards appropriate to the image. He will comment on a commercial portrait and make great suggestions and turn around and comment on something less conventional and adapt his commentary to that vision There are many, many others who have this ability. He just came to mind first. For myself, I have learned quite a bit on this forum, from posting my own images and from reading the critiques of others. Mainly it has been technical in nature, but that is fine with me because it helps me to make what I want to make, or gives me ideas of how to make something in a different way than the ways I have gotten used to.