Definition of accessibility - In the Baseline document (under the heading 'If the WCAG does not set the baseline, then how can we be sure that a site will be accessible?) it says "No site or content is ever completely accessible". In the Conformance document it says "Note that even conformance to all three levels will not make web content accessible to all people." I strongly object to these statements. All content can be made accessible. In some cases, content may not be accessible, but if the problems were identified it could be made accessible. As the main body representing accessibility I think it reprehensible that we have these statements.
Remove the statements. Merge Level 1 and Level 2 SC into one group called 'Mandatory'. Rename Level 3 to 'Advisory' or 'Optional'
The statements you refer to are meant to reflect the reality that not all Web content can be made accessible to all people. One of the lessons learned with WCAG 1.0 was that, for some individuals, even content that meets WCAG 1.0 AAA did not overcome the accessibility barriers faced by those with certain combinations of disabilities or with certain types of severe disabilities.
Regarding the proposal to combine levels A and AA as mandatory and rename level AAA to advisory or optional, the working group has received a great deal of feedback on both sides of this issue. We have chosen three levels because we feel it provides the best options for the different users of the guidelines.