I wasn't even going to mention the canvas tag, that feature alone has people building game engines specifically for web browsers. https://playcanvas.com/
Then there are the <audio> <video> <picture> tags specially for native rich media elements. Also, there is the "data-*" meta tag which means you can create your own custom elements which are added to the DOM tree. So you can create any tag element you think is missing from the HTML5 spec.
To say nothing cool has been added to HTML5 is low effort at its best and ignorant at its worst.