I think the parent might be slightly off the mark or simply is lacking detail.
One concern in nutrition is separating fruit juice from fruit pulp. You probably wouldn't eat three oranges in a sitting without feeling full but you can certainly drink three oranges' juice. That's the number of fruit needed to make a cup of orange juice.
If you're adding juice to a kale smoothy it's more complicated. At a certain point of extortion, refinement, and concentration that juice can become a proxy for simply adding cane sugar.
If you're blending your fruit and eating the pulp then there is no change.
One concern in nutrition is separating fruit juice from fruit pulp. You probably wouldn't eat three oranges in a sitting without feeling full but you can certainly drink three oranges' juice. That's the number of fruit needed to make a cup of orange juice.
If you're adding juice to a kale smoothy it's more complicated. At a certain point of extortion, refinement, and concentration that juice can become a proxy for simply adding cane sugar.
If you're blending your fruit and eating the pulp then there is no change.