Besides screen readers, using a single descriptive noun as the link text might help for maintainability in some situations. First, it reduces the chances of a given link accidentally getting copied to another section by an unscrupulous maintainer. Second, in case of a dead link with a non-obvious URL (like maybe some ancient sourceforge link to a now renamed project), the link text is an extra bit of information to remind you if and how the dead link should be updated (assuming no comment exists). I admit that's a pretty minor benefit.