Plastics, waxes, solvents, synthetic fibres and even pharmaceuticals. There are second order products from cracking like hydrogen which are important for things like fertilizer but that is rather carbon intensive.

You can use organic oils for some of these. However organic oils are more complex so need to be broken down into simpler building blocks which all takes energy and processing. Of course you also need to grow oil bearing plants which also tend to require a lot of fertilizer.