it matters if you don't want injury.
What injuries did he get from training?...wasn't his leg thing from slipping on ice?
What about Cutler's bicep injury?...with like a 25 pound dumbell?
I hear what you're saying, I'm just saying that you can train as strict as Dorian and still end up like him. You can train like Ronnie and end up like him. Both were multiple Mr Os, both trained very differently.
People gotta figure out what works for them. Yes, Branch's form looks terrible. But what does HE look like?...like a beast.
There's plenty to learn from the pros. If anything over the years, the 'textbook' way to perform exercises is not the best way (nor is it categorically the safest) to get muscle mass.
All things being equal, if a guy on gear trains like 'shit' and a drugfree guys uses the same form, what makes us think that it won't work for both? People gotta figure this shit out for themselves. Start with a textbook, but if it ain't working, then do whatever it is that allows you to get the most intensity outta the movement.