Flutter builds a parallel accessibility tree in the DOM that screen readers and search engines scrape. It's kinda cool, you don't have to rely on HTML, CSS and JS as the application layer, use something else like WASM for that, but for the document layer, use HTML. In a way, it's like the original purpose of HTML is preserved, as I see many people on HN complain about how the DOM shouldn't be used for applications and should only be used for documents.