En Why Accessibility Overlays On Your Website Can Make Things Worse podemos leer:
So that’s settled: Websites should be accessible to all users, regardless of their abilities. The real question for webmasters is how to reach this goal. Starting in the 1990s, tech companies began to offer third-party web products that introduce accessibility features to existing sites without altering the source code. Some of these overlays add text-to-speech capabilities to read page content out loud. Others include controls that allow users to resize text or swap out color schemes.
But the latest generation of overlays go further: They scan web pages for accessibility issues and try to automate fixes.
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These automated fixes sound helpful, but in practice they can be insufficient or even frustrating for the users they try to serve. For instance, auto-generated alt text is often strange and irrelevant, creating more confusion than clarity for people who use screen readers. Adjusted keyboard navigation sometimes fails. And the user interface control panels can themselves interfere with screen readers, braille devices, and other assistive technology.
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At best, then, these automated overlays are usually unnecessary. People who use screen readers or other assistive technologies must navigate to a website in the first place. They browse other websites and use other digital tools. That means they’ll already have assistive features integrated into their systems — and the overlay may interfere with these existing tools. In other words, to access an overlay widget, users must have already navigated to that widget, which means they likely have the tools they need.
