I'm not certain... but as I understand it, LEDs (while yeah, often made up of individual bulbs) just are what they are and that's it, while RGB (often made up of some solid shape) can be any color, controllable by... something. Gee, that would really suck to have like a Xigmatek CPU heatsink, an ASUS graphics card, MSI motherboard and Mushkin RAM, all RGB, and all controlled by their own software... you'd have to have 4 bloatware packages installed just to control your RGBs... unless there's a better way. I'm not really into the whole RGB craze, so I don't know exactly how that works.
Anyways, I just thought it was funny that everybody was grumbling about RGB when the OP specifically said the cooler does not use RGB, but instead LEDs.