Problem is - no one has bothered to do the math.
The daily calorie intake for an adult human is 2,000 per day. [LINK]
This makes the max sugar intake 100 calories ( 2000 * 0.05 = 100 ) .
Sugar is 4 calories per gram. [LINK]
This means that an adult human is only allowed 25 grams of sugar a day ( 100 / 4 = 25 ) .
With that math done, I looked up how much sugar is in 1 serving of common fruit [LINK]
I than compared it to the daily recommendation of fruit [LINK]
It turns out if you follow the new sugar guidelines the WHO has set out, you will have to cut back significantly on your fruit intake.
Taking into account all the food you eat per day, you'd be limited to 1/4 to 1/2 serving of fruit per day - the nutrition guidelines say you need at least 2 servings.
Edit: I received a comment below regarding "sugar types" ...
As some one who has unstable blood sugar, I can tell you this: glucose is glucose, regardless of were it comes from. A single apple will spike my blood sugar the same as a 1oz chocolate bar ( I checked ) !