Inbreeding doesn’t cause birds to “suffer.” The only common downside to inbreeding in chickens (after many generations) is slower growth and lower fertility but a less-fertile bird can still live a long and healthy life. At this point breeders will outcross to a distant relative and the cycle of inbreeding starts again. It certainly isn’t deformed and certainly doesn’t have a chronic disease. If defects turn up, an experienced breeder will breed them out. The inexperienced breeder will crossbreed because that will hide harmful recessive traits in the genes.Hybrids are almost universally hardier because they don't suffer from genetic bottlenecking. I personally try to avoid purebred animals out of compassion. So many chickens suffer from terrible inbreeding
On the other side, some hybrids like Cornish Cross and Red Sexlinks do suffer due to either fast growth or high production.