Hedging softens a statement so it sounds cautious and polite.
Cautious, not blunt
Blunt: junk food causes obesity.
Hedged: junk food may contribute to obesity in some cases.
Academic and polite
Few things are 100 percent certain. Softening an opinion is also good manners. A hedge is a measurement, not a fog.
This is the cause. — absolute
This may be one of the causes. — hedged