Very true. It's also a myth that all dogs are mature at 2 years of age. Siberians, mature slower, sometimes taking up to 3 years to be fully mature. Currently I have a 3 year old, nearly 2 year old, a 9 month old and 8 month old Siberians. The 3 year old looks and acts much differently than the others, the 2 year old looks good in body, but her bones and mind are still maturing and I can feel the difference in her legs compared to the 3 year olds. Both puppies look like someone put them on a torture device and stretched the crap out of them. Phantom may look and move akwardly until 2 years of age, then get the dignified majestic look as he matures at 3. This means he might not do well in shows until he is 2 and he should not pull weight or breed until he is 3 years of age. It is the same as human children, when teenagers hit a growth spurt and get uncoordinated because of how fast their body is growing.
And here is a bit of trivia for you, racehorses aren't fully mature until they are 3 years old. This is why so many horses racing for the triple crown break legs, and less older horses break down. Racehorses are a business and it's big money to win the triple crown, so they force the horses to race when their bones aren't ready and this causes massive injuries and damage to the young horses. So let us dog people take a lesson from racehorses and NOT do something similar with our performance dogs! (when I was younger I loved horses and horse racing. Until I discovered the truth about it. We lost great horses such as Barbaro, Ruffian, and countless others to greed). Please do not put a young, still developing dog in harness to test it and risk injury.
Oh a side note, Phantom gaiting is one of the funniest things to watch! He tries to gait, gets it for a few steps, and then his feet go everywhere! It kinda reminds me of what a dog would look like on slippery ice, the feet going in different directions, lol. The dog my youngest son is training with, by contrast looks great, but she is our 3 year old Siberian. My older son has decided he wants to learn agility using my Belgian Malinois. What started out as something for me to do, has become a kind of family thing. I just don't think I can fit 2 teenagers, 3 dogs, and all their supplies in my car.