The W3C‘s WAI‘s WCAG are just starting points. They are guidelines, to point us in the right direction. But they are not the be-all and end-all in terms of providing an accessible site. Some of the guidelines are useful, others are missing. And then there are those guidelines that are good in theory, but implementation leaves a lot to be desired. This is another case where human understanding of the issues is important.
Let’s take the styling of links as an example. WCAG does not specify styling links in a way that makes them obvious. For a while, there was a fad that removed the text-decoration underline from links. People complained they could not tell what was a link and what wasn’t, so we bolded link text to make it stand out. But that is not sufficient for many people. Relying solely on colour might be a problem also, as many people are colour blind! And if your visitors can’t tell there is a link somewhere, you have accessibility issues.
Some developers made a point of styling a:hover differently, so when a user moused over the link, it would be obvious it was a link. This is making it a bit more user-friendly, for sighted users with a mouse. But what of the sighted user that relies on keyboard navigation? They are not going to hover over each link. As a result, they are not going to be able to see what the link is, where it goes, etc.
That is why it is good practice to first style the links so it is easy for people to know it is a link. That is also why it is important to style a:focus and a:hover in similar ways, so sighted users, tabbing through your links, will know where they are and what is happening.
But that is not in WCAG 1.0
There is also the case of the Access Keys. Much has been said about Access Keys over the years. In principle, a brilliant idea. In practice, it is not particularly useful, as all too often the keyboard shortcuts used on the site interfere with the shortcuts for the operating system, the browser, or the screenreader. Plus, when each site uses different Access Keys, this technique’s usefulness fades quickly.
At the risk of sounding like a broken record, I will say again: It is important for developers to know the guidelines, and to understand various accessibility issues, because unquestioning implementation may not be sufficient.