Most people, including executives, consider much of marketing to be common sense. We're all consumers, so we all know how we respond to products, names, logos, advertisements, and PR, right? So we're all experts on what works in marketing, no?
Actually, psychology tells us that there's a lot we fail to perceive about ourselves, and that a lot of what we perceive about ourselves is skewed. We have a lot of "blind spots". And it's obvious that what works with us doesn't necessarily work with others. So the notion that we're all experts on marketing by virtue of our extensive experience as consumers is flawed.
Here's the money quote from Ries's article:
"When management has a marketing problem, it turns to its marketing department and says, 'We’ll do it my way because marketing is just common sense.' And no one has more common sense than the CEO, right?"