Due to the scapula being pinned to the bench and unable to move through their normal range of motion when the hands are locked on the same bar. I don't even bother with barbell anymore. Too much stress on the shoulder. I really dont see any advantage to a barbell bench press. Dumbells work the stabilization muscles more, allow full range of motion, allow different hand positions and you don't need a spotter as badly as you do with a barbell.
Barbell is for show and powerlifting as far as I'm concerned.