Handheld LCDs haven't used an edge light source in years.
Nowadays they use a flat light panel, often made with white LEDs. E.g.
View attachment 715241
Indeed, what I meant was the driver for the backlight. From The Verge review:
Because something has to drive the backlight under the screen, going with LCD also means there needs to still be a small "chin" bezel on the bottom of the phone.