To answer that, you have to ask yourself why somebody would not want to create an abstraction between content and presentation for their website. It's a basic aspect of modern web design, and even when it gets implemented, it's only ever used to present in one way. Why would someone do that? I'm sure there are a multitude of answers, the most basic of which is "they didn't feel like it." They probably didn't feel like it because they didn't think their efforts would be rewarded, or it wasn't personally fulfilling to them.