Because they can’t be inflated by fan, require more bridle lines (presumably), design window is a lot smaller as a single skin kite will easily buckle, etc.
Like I say, single skins are very interesting, but they are at a more advanced level, construction and handling wise. Also to this date I am not aware of really large single skins with higher lift to drag, big wind range, gust handling etc.
The closest we have are probably Flysurfer Peak and similar kites, which actually have many other design elements compared to a normal twin skin paraglider style design.
The comparison is really gross if you compare single skin kites to LEI. LEI’s are produced at much lower cost to foil kites, simpler design, more precise control of performance etc. It should be clear single skin kite is kind of a non-starter these days for any project wanting to produce electricity, because the single skin technology would have to be developed first, and many talented people have struggled their whole life doing only that.
To be very specific, I don’t think Afrokite is a huge step in the direction of developing a single skin kite at huge scale, with handling and higher aerodynamical efficiency.
Parachutes causing drag is of course a different matter, but I am still thinking about more mainstream AWE concepts here (hovering/bounding with crosswind flight)