You are correct, the LED does provide the back lighting, suppose then the only benefits are less power and thinner, unless LED can offer better contrast?
The backlighting is responsible for brightness, power consumption, illumination uniformity and color temperature.
Contrast is only influenced by the panel.
I also think that LED mainly give reduced power consumption/heat. RGB-LED may give some benefit in that global color temperature adjustement can be carried out without spending panel contrast.