Maybe you don't know the difference between muscle shape and muscle proportions .
From you:
''no one ever changes their proportions''
''Big Ramy - will always be quad dominant.''
''Warren - will always be quad dominant.''
''Dorian - always slightly undersized arms''
BTW I'm done with this nonsense.
I do know the difference. I just don't think Arnold's pecs were lagging in the beginning for example. Kind of hard to compare the pics too because the poses aren't held the exact same way.
But from what I've observed in real life as well, the proportions of a beginning trainee become apparent quickly and it's very hard to change them through training. It's as if the body grows how the fuck it wants, regardless of anything you do. A while ago me and a friend laughed about this because his traps seem to have grown the most out of any bodypart and it's the only part he doesn't train directly.
But sure, I would emphasize weak bodyparts as well in training, it's just that it doesn't work that well.

But even small improvements would be welcome of course.
Tom Platz never got his upper to match his legs despite only training legs once a month and killing his upper body.
No one would resort to injecting oil if it was simply a question of prioritizing in training.