What two characteristics do fungi lack that forced them to become decomposers

Fungi are decomposers, they obtain their food from dead organic matters. Fungi obtain their nutrient this way because they can not produce their own food. To produce their own food they need chloroplast in their cells to obtain energy from the sun. And they also need the ability to fix nitrogen which they will incorporate into the food they produce. Because they lack the ability to do this thing, they have to adapt to eating dead materials.