Feathering is indeed used for demand control.
Typically this is also the first thing they do upon an increase of wind speed. Then they rotate the entire head of the mill out of the wind, and if nothing else works there is a mechanical brake working on the transmission. I have no idea how this could have happened and never read an actual explanation, only general alternative energy sources bashing.
The more realistic supporters of renewable energy always underline it is important to spread power generation over several different sources and large areas to level out wind, sun,... influences. Another method is to use any excess power generated to piower pumping power stations that will in turn produce power in low wind times/ at night. A healthy mix is the key to success and a stable power supply!
The thing that sets the US apart from the 3d world is the reliability of our power infrastructure and I think that will go away.
It already seems to have dropped considerably with decades of low maintenance and decrease of generating capacity after deregulation. Failure is not inherent of certain systems, it's caused by bad judgement.
