(To your point, it's almost impossible to imagine we'd be able to operate it at a scale that makes a genuine impact, but these are all chaotic systems and a couple percent here and there can compound to keep things on the right side of the phase shift.)
For reasons of thermodynamics, pulling water out of the air uses more energy than desalination, and that's before the fact that you have to have a large fan to move a large volume of air to get a few drops of water.
It is on the order of using 60X as much energy to dehumidify air if you are trying to produce bulk water, rather than just desalinating water through a method like reverse osmosis
The applications of condensate water sources typically aren't in areas where desalination is the competing technology -- usually the competition is piping water in from far away via a utility system.