The example that Google shows in their post has accessibility features [0], although currently these need to be switched on with a keyboard shortcut (⌘+Option+Z).
Pay attention to `document.getElementById('docs-aria-speakable')`.
Yeah it's pretty bad to have accessibility be a mode though. Also, since it's completely non-standard, the usual screen reader navigation keys don't work as expected and users have to learn a completely custom interface. Better than nothing but it's not great.