Many tropical fruits are seasonal, and found in great abundance when in season. As the season ends, competition for that particular fruit might heat up, and they might turn to the semi-fermented leftover fruit under the tree.

Just to note, this behavior was not mentioned in the article at all.

Yup, but as I live in the tropics, I can speak confidently about this behaviour, having witnessed it, experienced it, and participated in it in my childhood years swinging through mango trees.

What an awesome childhood, I hope.

It was. Best days of my life. I wish I could have given my own child the same.