I think that's a bigger myth than people want to believe, or bad/old information. From Bomb and Gouge:
The USGA is unequivocal about average golfers: Despite decades of naysayers and experts alike suggesting that the average handicap is not dropping, has not dropped and never will drop, the fact is, it has. Let's say that again: The average handicap of all golfers -- men, women and children -- has decreased consistently for the past 15 years. The average handicap today is two strokes better than it was in the early 1990s, according to research provided to Golf Digest by the USGA's Golf Handicap & Information Network (GHIN).