Many people with visual impairments (i.e. screenreader users) find it hard to use WYSIWYG word processors like Microsoft Word. One slip of the finger and SUDDENLY YOU’RE TYPING ALL IN CAPS OR ITALICS OR WORSE.
Sure, screenreaders can announce boldness and font and italics as you go, but given every character can have dozens of attributes and you need to get on with your writing – that is, you want to work on the actual text, not what it looks like – that quickly becomes unfeasible. But you want to work with more than plain text: you want to use font and bold and other rich text formatting, because people expect that and it can help with understanding for sighted users.
A better solution for at least one blind user is Markdown. This is a plain-text way of writing formatted text: you write in plain text, but you use a special subset of HTML to add formatting like tables to your text. Then it converts from your Markdown to valid full HTML documents, which look great in Word or can be easily converted to another format.
It’s not for everyone: many users would probably be better with some way of restricting the formatting they can apply so that they can’t go wrong. But for technical screenreader users it might be a way to create attractive formatted text far more easily.