It's a basic DOM element — a block of content. Without native support, it's simply shown by default, instead of hidden by default, so nothing is broken, and eve

It's a basic DOM element — a block of content. Without native support, it's simply shown by default, instead of hidden by default, so nothing is broken, and even the default on non-supporting browsers can be changed with JS and CSS. If anything, this is the works everywheriest of things that "work everywhere" in post-2010 web development. Some other stuff actually breaks accessibility by default.