Screen reader users navigate websites using a variety of techniques. One of those is to pull up a list of links (a feature of most screen readers) and navigate through that list. Given this, link text should be able to stand alone independently of its context. For example, links like “click here” and “more” are meaningless out of context.
Also, speech recognition users can click links with a voice command like “click” followed by the link text. Therefore it’s helpful to keep link text short and easy to say.
For both of these reasons long URLs should be avoided as link text (short URLs like washington.edu are ok since they’re easy to say and stand alone independently of context).