Note: God work through human beings to fulfil his plans on earth, since the earth was created for man as a reflection of God and His kingdom above, that's why though Jesus was God ( Philippians 2:1-12 ), He become a man to save humanity. In other hand God does not have any need, because He is self sufficient. But when it comes to calling humanity back to himself, He always looks for a person, who will be obedience to His will, since humans have their own will too and chose to live in rebellion at all time.. I hope this make sense.
For In Example Ezekiel 22:30 God said, And I sought for a man among them, that should make up the hedge, and stand in the gap before me for the land, that I should not destroy it: but I found none. So God has no need but looks for obedience people to serve Him and to call others back to him, so you see God want to work through us, so make your self available rather than arguing with being fruitful to God.