Nothing, I think the parent is wrong or misspoke. The advice is usually "substitute bad processed sugar with fruit", which is what Dr Lustig has advocated for the last decade. Of course too much fruit is itself bad, since the fiber can only do so much.
A balanced diet is important. Fruit only covers certain parts. And yes it also has a bit much sugar. Replace 80% of your fruit with veggies and you will be better off.
I agree, but most people should start by replacing most of their food with fruits. All their carbs and sugars should come from fruits first, and once they master that, they can try replacing some of it with veggies.
Sorry, didn't mean mostly fruit. I meant to say that it's best to start by replacing all your sugars and most of your carbs by whole fruits instead of veggies. And I say that only because it'll be easier to achieve, and still better then the alternative processed foods.
You should also have fish/meat, nuts and seeds for proteins and fat. And if you can, do have veggies instead of sugar rich whole fruits. But its hard enough eating healthy, I've found that the first thing to do is focus on eating better and not the healthiest. So fruits are the best deserts, and are better then most snacky thing people eat between meals. Yet they're easier to adopt in your diet because most people find them tastier.
For example, I see some people who when hungry and looking to snack down a whole bag of chips, or a whole box of oreos without thinking. But who'd mentally find it excessive to down a whole container of strawberries. Changing that attitude is a good place to start, and eating a whole strawberry container instead of a box of oreo is a pretty easy and simple change. Easier then just not snacking at all, or then eating coliflower instead.
