You have probably seen the pitch: paste one line of JavaScript and your website is instantly ADA compliant. We understand why that is tempting, and we will tell you plainly — it does not work that way.
Overlay widgets bolt a settings toolbar on top of your site, but they do not fix the underlying code. If your form inputs have no labels, your headings are out of order, or your menu cannot be operated with a keyboard, those problems are still there under the toolbar. Many screen reader users disable overlays entirely because the widgets interfere with the assistive technology they already know. And businesses running overlays continue to receive demand letters, because the barriers the letters describe were never actually removed.
Our position is simple: accessibility lives in the markup, the contrast, the labels and the interactions — so that is what we fix. It is more work than pasting a script tag. It is also the only version that actually holds up.