and your right to a point. But putting Bench Press into any chest day allows for an excellent compound movement plus warms up the muscle before isolation training.
Ive continually heard this over the years that people don't get much growth from doing flat bench press but then again you really start looking into their programs and you see there are movements that they don't do or have weak points that follow from not going bench Press.
Granted alot use bench press as an ego lift but at the same time if they train smart with it the payoff is immeasurable.
I will also add to an Total Pec size is not determined with Bench Press. you want to build an excellent upper chest then do Incline Presses barbell or Dumbbell. Yes, I agree with this. But bench Press should never be counted out.
Also doing Back work. You want a big chest or a big bench You have to have a strong back. what we tend to not look at is the whole picture. Each muscle is dependent on each other. It all works together.