Your full of shit, as has been said back those claims up.... 18" arm after 5 yrs training, 18" another 20yr later
And now, just prove it.
If that what you write is from your own experience, I am sorry but you can't generalize it to affect the whole human race, because lot of us are better in this sport than you are. You see, you seem to know it all, but at 57 and after 30 years of training, I am still learning. After I found benefits of full range of motion and good posture few years back, I have make better gains than in any part of my earlier life, added inches of muscle all over and feeling better than ever. This is out of your reach because you know it all already, there is nothing to learn for you..

For example, why don't you try these full range squats or Platz hacks? Oh my knees hurt so much, bo hoo hoo

....