The clue is in the word 'design': most people think of a website design as totally taken up in appearance and images. The look of the potential new website is what they want to see first. That is completely reasonable: how a website looks at first glance is extremely important, especially if it is supporting a business.
Once the 'design' is taken care of, the next step in the process is to add all the necessary information - all the content. Many of our customers use the 'design' phase (the phase where we create the appearance) to gather up the information that they will eventually add to that design.
This two-step process is so ubiquitous in website design that most designers use placeholder text and images in the first step, creating beautiful eye-catching arrangements.
The problem comes when the 'real' content replaces the placeholder content, and the customer discovers that...