On my perception idea and product/service both are important for a business.
A product is a tangible item that is put on the market for acquisition, attention, or consumption, while a service is an intangible item, which arises from the output of one or more individuals.
A business idea is a concept that can be used for financial gain that is usually centered on a product or service that can be offered for money.
So, business depends on both (idea and product/service).