When leaves fall, the leaves accumulate harmful substances. However, fallen leaves are considered

When leaves fall, the leaves accumulate harmful substances. However, fallen leaves are considered a good fertilizer. Why?

The plant removes toxins into the leaves, which accumulate over the year. Therefore, burning them is strictly prohibited. This poisons not only the environment, animals, but also people themselves. But fertilization from the leaves is very good. This is due to the fact that plants do not use leaves as a source of anything. First, the leaves are processed by worms, various bacteria and other organisms. This is how all harmful substances are broken down. These substances can already be absorbed by plants along with water through the root.