First- Thank you for providig the link.
Secondly narutowiki is an essasy written by people like us- So I am going to take a chance at the explanation:
It seems my guess was not tatally wrong and they did involved kakashi's example for given KG. Anyway.. Dust release involves three elements- earth wind and fire. I think to use this tech the shinobi must have a master control on all three elements. just like wood release needs perfection with water and earth both elements.
The KG related with Eyes are more common than those which involve elemets. as we have seen that elemetal affinities may differ within the same clan. and even if one element is common, the other may not be so and thee total combo may turn out diffeent. Like Hashirama had Water and eart perfection. Tobirama was master at water and could create water without any water source but probably had not that much control over eath element...
Different people may end up (it would be rare but possible) with same elemental combination and level of mastery- especially if they get a right teacher to learn...
Just my two cents.