If the definition constantly changes, no one gains the confidence to challenge the people enforcing the definition; they can change it at will to suit their nee

If the definition constantly changes, no one gains the confidence to challenge the people enforcing the definition; they can change it at will to suit their needs, and revel in being hypocritical because they know there's no consequences to it. The demoralization takes hold that the system cannot be questioned or fought against, and any resistance fails.