Unfortunately there are hardware limitations that prevent HDMI from being able to do this. One of the features built in to DisplayPort was being able to power multiple monitors off one output, so this device is just utilizing that ability. HDMI doesn't have this feature.
You guys seem to miss a large portion of the video cards out there, Sure Gaming video cards support up to 6 display outputs, but your work video cards, such as the quadro cards have very limited video outputs, and this can be greatly used by graphic designers or cad/cam operators. Its not all about the gaming environment.