In the old days when you benched you had to touch your chest and wreck your shoulder if you had long arms. If you look at top bench press guys thay have a barrel chest and short arms they never break parallel the bar moves maybe 5-8 inches tops. When you go past parallel your shoulder is in its weakest position now you have to change the direction with the bar and that when most guys hurt their shoulder. I even saw a big guy rip his pec off pretty gross with only 275 going deep not worth the risk. I hear guys say they go for the stretch I wouldn't like to stretch my muscles and tedons with all that weight, stratch before and after you workout.
I been a trainer and strength coach for the past 17 years. I learned that from many years os school and experience and my own lifting.