Culling is much more humane than dumping. I do think people should exert a reasonable amount of effort to rehome if culling is not their first choice, but they need to step up and take responsibility and do what needs to be done if it means the animal suffers less.
Lazy, lazy, lazy!
If people don't want their birds, they need to rehome them, give them to a shelter, or cull them. It's lazy and irresponsible to dump them like this.