La opinión de la American Foundation for the Blind sobre las capas de accesibilidad

En Accessibility Overlays: Promises and Pitfalls:

These accessibility overlays can also break your website completely by applying automatic fixes to the few issues mentioned above, which means risking your website’s user interface as changing the structure impacts how the page is being rendered. Though some vendors do claim to provide manual testing and remediation, often the remediation is only applied to the overlay script and not to the inaccessible underlying code. If the overlay is blocked by the user, the inaccessible underlying code is fully exposed.

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Unfortunately, the accessibility overlays generally don’t fix many issues, and they can even make things significantly worse. Only a small subset of problems can be detected automatically, and many of those still require human judgment to evaluate. We’ve also seen some examples where the overlay UI controls themselves were inaccessible.