Being a salesman all through my life and across different industries, I do not agree with it.
The author probably has not heard that best marketing is "word of mouth marketing" and if the product is good, it automatically happens.
No blitzkrieg marketing campaign is needed then, and I have not witnessed this in one industry but every industry.
When one has awesome product, you require only sales; when one has sub-optimal product, you require both sales and marketing.
Give me one example where a product took off because it was marketed well , even though it was a suboptimal product.
And this is specific to the new breed of hoodwinkers called, "Growth Hackers".
It has never happened!
Hence, focus on the product, rest will follow!