I only have wikipedia-level knowledge, but my understanding is that turbines are heavy, and wind power spent holding the turbines up is power that isn't converted to electricity. If you want to put the turbine up high, you can save power by just building a traditional fan-on-a-stick wind turbine.
Lifting things requires power, there is a formula for work done. Keeping things up does not require power, a chair does not collapse under you when it runs out of battery.
A ‘normal’ wind turbine generates a huge force on its foundations when it operates - that’s why they have to be so heavy. It’s not moving so no work is done.
That force does not care what is opposing it - whether it is fighting the strength of the tower holding up the turbine, or if it’s fighting gravity and a steel cable holding the kite. As long as the forces and their directions cancel out, it’s all the same.
Lastly, waste does not matter, wind power is available for many kilometres vertically.
If a kite is flying 500 meters above ground, it can suddenly access the power a turbine could not.
So if it accesses power that was inaccessible before, it’s a win even if half of it is wasted.
Lastly, none of this discussing has any relevance, only economics matters.
You care about cost of equipment, how long it lasts, how hard it is to repair, how many people are required to operate it and therefore salaries, where can you build it - a system could be 100% efficient but unprofitable.
