WYSIWYG editors have a hard enough time generating valid, sensible markup and styles for consumption by typical end users. But many end users are not typical -

WYSIWYG editors have a hard enough time generating valid, sensible markup and styles for consumption by typical end users. But many end users are not typical - some have visual and/or auditory impairments. In many jurisdictions, website creators are legally required to comply with accessibility (a11y) principles. This adds another layer of abstraction on top of the already complex task of building a valid and functional UI.