To gauge the likelihood of minimum viable products being accessible, I think these are some of the most important questions: 1. How common is it for web applic

To gauge the likelihood of minimum viable products being accessible, I think these are some of the most important questions: 1. How common is it for web application developers to directly make part of a page clickable without using an appropriate semantic tag or ARIA role? 2. How common is it for web application developers to roll their own widgets, e.g. buttons, menus, or sliders? One has to assume that most such widgets implemented directly by the application developer won't have proper ARIA support. 3. Which reusable UI components and toolkits are most common among web application developers, particularly those working on a minimum viable product? How accessible are these?