Because of what they contain, some contain nutrients, calcium, iron, potasium and stuff, all of that is good for the body, so the fruits are a natural way for your body to have all that with out seondary stuff.
because it have many nutients that are healthy. im not sure with avocado since its the fruit with the most calories, but it can gain you healthy weight.
They have lots of vitamins/nutrients and can help your skin and hair be more healthy
Because they aren't filled with crap and they have vitamins