A mass of air will travel from an area of high pressure to low pressure whether or not there is a wind farm in the way.....where would the energy extracted by the wind farm otherwise exist. Is it theoretically possible to alter the energy balance if a wind farm were vast enough.
Sorry, the link editor is trying to be clever by converting my absolute URL to a relative one... and messing it up. I've removed the link - you'll just have to C + P.
Wind turbines absorb some of the energy of the wind, but so do trees and buildings. A large forest slows wind speeds to a much greater extent than a few wind turbines.