Joel performed the duty of a watchman in his day. He was addressing those in Israel who were asleep and should have been more alert. In addition to being intoxicated and not watching, the people were in a stupefied condition and had difficulty reasoning in a rational fashion.
From the spiritual standpoint, those who have been imbibing the false wine (doctrine) of Christendom are intoxicated and asleep. The “drunkards” need to wake up and realize what is happening, but because they fail to watch and sound an alarm, they will sleep through the doctrines of demons in the coming church-state hour of power. However, a time will come for shock and renewal. The old wine will wear off, and a new experience will come upon them—a radical change for which they are ill prepared.