This article you've found sounds like a vital piece of avian medical information not to be missed by parrot owners[I am saving it-thanks for posting!] but still begs the question as to why most parrots do not feather pluck.Here is the possible link to "The Avian Medicine Chest" mentioned in the article and mentioned in Birdtimes.com http://www.avianmedicinechest.com/login.asp?Redirect=/Default.asp
Perhaps the observation of various bird species in the wild has revealed a yet another more vital clue in the diagnosis of feather pluckers. I get the impression though of the larger parrots which pluck as perhaps experiencing a sensation of "bugs" which those suffering from psychosis sometimes do. Maybe too, a spray preparation of the formic acid will be created to minimize this behavior in captive parrots? Also, maybe in outdoor aviaries the inclusion of ants native to their habitat would be beneficial?
.."Anting is a bizaare behavior which can be observed in either a passive or active form. In passive anting, a bird will stand or lay very still on an ant hill or mound and allow the ants to swarm in and out of his feathers, biting the skin. When I was a child I made the mistake of standing on an ant hill where a lot of angry red ants resided. I don't recall finding any part of this time as particularly pleasurable or soothing, Maybe the birds feel it is the lesser of two evils since it's been suggested the chemical formic acid which is richer in biting ants than in the more easy going species, may be used as a natural form of chemical defense in repelling infestation by ecoparasites.
In active anting, a bird will pick up ants in their beak. The bodies of the ants are then crushed to release the formic acid, and rub this "balm" over the skin, through the tail and wing feathers and occasionally the back or other body parts. Birds have also been seen holding the ants against their skin, allowing the ants to bite particular locations on their bodies. This sort of grooming activity is carried out through a series of twisting, turning, and extreme contortions. It's been suggested birds use the formic acid in the ants as a sort of grooming ritual to remove or thwart off uninvited parasites such as lice or mites. Dr. Stephen W. Kress, a research biologist with the National Audubon Society says he believes birds use anting behavior to stop pain and itching from new feathers as they grow in. If that is what Venus is trying to imitate, she has an interesting technique which makes her antics a joy to observe."