I think Mark's post was meant to inform people of the nature of the Web design and development process, and all of the different roles and responsibilities that go into making this process work effectively, more than anything else. I agree with Tim that each of the roles outlined above are not required by every organization or every website.
But still, I appreciate Mark's post because it makes organizations aware of whats involved in the process. To me that's a good thing. And like Tim pointed out, at the end of the day having a beautiful site is not what's most important; rather your efforts are much better placed in making sure your content is of high quality to your audience.
If you want to ensure you have a good site, just keep the following rule in mind:
"Content is king but presentation is his queen."
In other words, while it's most important to provide your visitors with excellent information that is relevant to them, having an aesthetically appealing site will also make your visitors happy. This doesn't mean that your site has to be super glitzy with all the bells and whistles! Quite the contrary -- so many sites work quite well by just being simple and elegant.
Yann