I love, love, love all the little details of HTML that Aaron offers up here. And I really like how he positions non-visual user-agents like searchbots, screen readers, and voice assisants as headless UIs.
HTML is a truly robust and expressive language that is often overlooked and undervalued, but it has the incredible potential to nurture conversations with our users without requiring a lot of effort on our part. Simply taking the time to code web pages well will enable our sites to speak to our customers like they speak to each other. Thinking about how our sites are experienced as headless interfaces now will set the stage for more natural interactions between the real world and the digital one.