There are so many ARIA guidelines on implementing alerts, modals, comboboxes and anything in between. Yet most don't have any equivalent presentational or functional counterparts in the existing browsers. Writing this comment, just as I'm writing an accessible combobox in a project where I'm not using any frontend framework and minimal JavaScript.
Let’s extend this thought a bit deeper. Why are we consuming different brands of fixed-form content through bespoke interfaces? Why is there no standard for navigation of any type of content?