The lack of emphasis on video.
The iPhone is a portable movie studio that occasionally can send messages or make phone calls (poorly).
If social media was still largely text based, BB would be a more efficient device. Unfortunately, it has morphed into a shallow, rich media platform. What gets attention: TikTok dreck, Britney Spears and her wild Instagram videos, not elegant prose. We as a society can't look away from the trainwreck.