Peter Drucker claimed, “…Because its purpose is to create a customer, the business has two – and only two – functions; marketing and innovation. Marketing and innovation produce results, all the rest are costs.” (More)
There's a shocking but simple truth in this. I've helped to evaluate many businesses over seven dimensions. The first of the seven is Marketing; and the last is R&D.
Marketing is all about finding a customer: it doesn't matter how great your 'ice cream' is until you can find someone who likes it and is willing and able to buy it. Sales is the process of meeting their desire or need (for 'ice cream') in a timely fashion, helping that prospect to spend their money with you rather than someone else.
Innovation or R&D is about developing a better 'ice cream,' and differentiating yours from the others available.