Accessibility is more than just screen readers. Toasts are also not accessible for folks with low vision, low peripheral vision, etc. And the time-based disappearance is unpleasant for many people, as one of many examples of "accessibility improvements are also often usability improvements".
A message that you have to explicitly dismiss, and that's stored in a "message history" somewhere, is much more accessible and usable.
A message that you have to explicitly dismiss, and that's stored in a "message history" somewhere, is much more accessible and usable.