How is it different from this bookmarklet?
If you're looking to link a citation to a statement, having the text is far more useful since the person following the link doesn't have to now find the statement in a potentially large and broad section. Also, if the page has since changed and the text no longer substantiates the cited claim, that'll be immediately apparent.
The hope is that this is useful and adopted by other browser engines and links like this would eventually be interoperable.