Why did the Israelites have to wait for God's power instead of overthrowing the Egyptians themselves?

Les explains that the Israelites were like a locust wrapped in a spider's web—they had no way of doing anything. They had no arms, no swords, spears, or shields, and no way whatsoever of overthrowing their Egyptian slave masters. Therefore they had to wait completely for the power of God to come in on their behalf. Even so, they were not a disorganized mob. Les points out that they had tribal organization, and Moses communicated with the several million Jews through the heads of the tribes, much like a military command passing down a chain of command. That organization, however, did not give them the military capacity to overthrow Egypt; their deliverance still required God's power.