¿Qué son las características accesibles de un sitio web?

En What Are Accessibility Features of a Website? explican qué son las características accesibles que ofrecen algunos sitios web:

Website accessibility features are the elements of a site designed to improve the ability of people with disabilities to independently use it. Sometimes websites include extra options specifically to enhance some people's use, but usually accessibility features are integrated into a well-coded website that is accessible by default.

Aunque normalmente estas características que se añaden con muy buenas intenciones, a veces pueden causar problemas a ciertos usuarios:

Sometimes, extra accessibility features are added with the best of intentions, but in practice can actually cause new problems. For example, some websites or digital tools will include their own screen reading technology with the goal of providing easy access to people who are blind, have low vision, or otherwise benefit from hearing content instead of or in addition to seeing it. However, many people who need to use screen readers already use one and likely have a go-to screen reader they prefer for that particular type of content, web browser, or device. In this example, the extra screen reader might interfere with the native screen reader, or vice versa, and accessibility will have been compromised, not improved.

Another common example are keyboard shortcuts. Some websites will offer custom keystroke combinations designed to save the user time or make interaction easier, and sometimes these can be helpful. Other times, however, keyboard shortcuts might interfere with screen reader or other assistive technology commands, or with keyboard shortcuts that users who need them most already have programmed. Again, in this example, something intended to improve accessibility can make the website unusable if not done carefully.