Fruits have fiber, polyphenols, and rare sugars. I don't know which of these helps control the risk.
You are invoking a fallacy known as 'begging the question' in that statement because you never establish that any of those things control the risk, just that they exist in fruit.
Maybe the fiber helps?
Fiber is great for gut health but it's actually works against nutrient absorption. Increasing fiber intake requires increasing intake of certain vitamins, possibly with supplementation.
It's better to eat things in moderation and know what antinutrients are in what foods. There are tradeoffs.
Exactly. Fiber sucks up some nutrients so they are either pooped out due to limited digestibility of the colon, or get consumed by gut bacteria.