For a very basic, unstyled textual Web page, accessibility is not usually a problem. Remember, accessibility is not just about making a page readable by people with disabilities, it's about making it readable by everyone and anyone.
Well, let's narrow the field a bit here. 'Everyone' and 'anyone' is a tall order. How do you make a photographer's portfolio site accessible to people with impaired or no vision? How do you make a music site accessible to people who can't hear? How do you make the photographer's web site accessible to someone browsing the web with a PDA device or the music to a computer user with no sound card? Sometimes, it is just not possible. Sometimes, it is inappropriate. In fact, once you get beyond the concept of 'Text', delivering 'accessibility' becomes more difficult.
Having established 'what' we are trying to communicate, we also need to know 'who' we want to communication with. In targeting our communications, are we using a sharpshooter's rifle or a farmer's scattergun? One is a precise message to a very select group of people and the other is a broad message to as many people as we possibly can.
This site, for instance, takes the rifle approach. The information and the audience are very specific - graphic design for the Web.
Other sites such as CNN or BBC News are aimed at a much wider and more diverse audience. The news sites publish in multiple languages and the BBC also has a low bandwidth, text only version of its pages. Both sites have the resources of major organisations behind them and are accessed by people from all over the World.
So, how do the accessibility requirements of WPDFD and the news sites differ? I can't publish multi-lingual versions of my site. I do it all by myself in my spare time with a budget of zero. Luckily, I can narrow things down quite a bit because I know something about the audience. If they are interested in graphic design, colour, typography etc. they are likely to have appropriate computers, screens and software programs. They are unlikely to be using a monochrome screen and running MSDOS or surfing with a PDA. The news sites have to cater for the lowest common denominator of equipment and software, I don't.
It is inconceivable that anybody genuinely interested in music would not have a soundcard and speakers on their computer. The news sites might have video or audio clips, but they are extra bonuses for those that can use them, not essential to knowing what is happening in the World.
In designing for accessibility, identifying and then catering for the intended audience is fairly fundamental.