The pictures/video prove everything. He will never have the best back in the final callout.
Nor the best arms, or chest, or quads, or hams. But hey he has one of the best shapes and abs in the line up.
The pics/vids prove that his back is lacking thickness. Up until recently, it was shallow, now it is less so. It's not about "insertions", but about thickness. By doing more exercises that target thickness and detail, he will and has made improvements. Because he has made improvements, shows that it is not about "insertions". It's about doing what needs to be done to get the muscle thickness. Also, muscle maturity is bro science AFIK there is no medical term called "muscle maturity", otherwise Shawn Ray at 22 achieved muscle maturity early. And his style of training that Rhoden was known for didn't help him, either. It's not as back as Dillett's training (that is hard to beat).