Connection of Cadbury’s Dairy Milk and Petroleum

What is the connection of Cadbury’s Dairy Milk and petroleum?

One of the ingredients is Ethyl Vanillin which is artificial Vanilla flavour
Ethyl Vanillin is produced from Catechol (also used in pesticides and perfumes)
Catechol comes from Phenol (also used in producing nylon, detergents and pharmaceuticals)
Phenol is produced by Oxidation of Cumene
Cumene is produced from Benzene which is a natural constituent of crude oil

So every chocolate has a tiny part coming from petroleum.