This is a partial myth and a scare tactic. Most bones are absolutely fine for dogs as they are built to crush, consume, and digest them. Chicken bones, when fed RAW, are actually soft and easy to chomp to pieces. Most meat chickens, as opposed to laying hens or turkeys, are also fairly young when they are processed (about 5-6 weeks old).
***Please note, this is very important: DO NOT FEED YOUR DOG (OR CAT) COOKED BONES. Cooked bones, especially poultry bones, can splinter and harm your dog. Cooking bones removes all their moisture leaving them dry and brittle, and when they splinter they can do so in sharp shards.
Raw bones, on the other hand, are easily digested, especially when they are still located within the meat. If you take a look at your dog's poo after a boney meal, you will see that the bone will either turn the poo chalky and white, or if larger pieces are present they will have a rubbery consistency (feel free to use the "stick poking" test, lol).
The best thing to do is supervise your dog whenever feeding bones (and in general) so that you understand how your particular dog eats; whether he is a gulper, a nibbler, or a gagger. For example, if your dog is a gulper you may not want to feed him turkey necks, at least not until he figures out how to eat them.
Please also check the other questions for more information on bones.
