According to a quick Google search, a mango has 46 grams of sugar (primarily fructose).
Now from what I understand, eating fruit isn't an issue, primarily because of the fiber that slows the sugar absorption process.
So eating the mango, which has about 11.5 teaspoons of sugar (1 teaspoon = 4 grams of sugar), shouldn't be a problem.
However, would my health be significantly, negatively impacted if ate 11.5 teaspoons of straight sugar and paired it with some fiber? Of course I am not getting the other benefits of fruit, like vitamins, but will this be bad for my health (bar the potential tooth decay).
Perhaps a more practical example - drink a can of soda along with a fiber-rich food.