There is a common accessibility pattern where the first tab focusable item is a "Skip to content" link in the top left corner. The link is initially hidden until you tab to it. That is the only use case I could think of when checking it out.
That's not what it's for, that's solved by showing the link when it's focused.
My guess is there was a desire to make Find-in-page automatically expand <details> elements and someone realized they could make it also work for custom disclosure widgets by giving the boolean attribute `hidden` an optional value.
My guess is there was a desire to make Find-in-page automatically expand <details> elements and someone realized they could make it also work for custom disclosure widgets by giving the boolean attribute `hidden` an optional value.