The point is that even with 100% efficiency (as in extracting 100% of the water the air holds) you couldn’t get enough water out of the air because the dry air simply doesn’t hold that much water.
At, say 20°C, 100% humid air only holds about 17l of water per m³ or in other words, if you are in a dry climate where the air has maybe 30% relative humidity even a device extracting 100% of the humidity from the air would yield only maybe 5l per m³ of air it processes. You would literally need to pull in 200 m³ of fresh air (as in air that has not been through your device before) to get a single m³ of water and any practical device operating at less than 100% efficiency would yield lower results than that. Also, forgot using this at much colder temperatures than that since that drastically lowers the water carrying capacity of air.