- Auto-generating content from the filename of an image is not suitable
  alternative text; alt text that isn't fully considered can be
  distracting and fatiguing for screen readers users (blind, low vision,
  dyslexic people).
- Setting a filename fallback short circuits screen reader default
  behavior and configuration for blank descriptions.
- Setting poor defaults also creates false negatives for accessibility
  linting and testing software, that makes it harder to improve
  application accessibility.

***

- After this change, if authors leave images without alt text, screen
  readers will fallback to default behavior for missing alt text.
- Also with this change, Automated linting and testing tools will
  correctly generate warnings.

[Fixes #30096]