[hamidnazari]

By W3C validator do you mean the Markup Validation Service or the Web Accessibility Initiative aka WAI? I think WAI validators were introduced to address the issue you raised in your experiment. Is this true?

Anyhow, I can't agree more, "being W3C valid means jack".

[kjhughes]

While being "W3C valid" (passing validation according to a DTD or schema for the HTML) is insufficient, it's still useful in that tools, including screen readers, can more reliably process the content of a valid page than an invalid page.

[silktide]

Yeah I agree, it's useful as an absolute bare minimum. But you shouldn't just get the green tick and rest on your laurels