Just because Dorothy started her career with D.W. Griffith does not make her an automatic pioneer. She did not invent a lens or the close up.
Dorothy did pen at least one scenario that was adapted by Dell Henderson and made into a film, the 1913 The Suffragete Minstrals. Dorothy appeared as an extra in the film.
Where Dorothy really was a pioneer was that she left Hollywood to make films in Great Britain. Hollywood, particularly postwar was the center of the universe when it came to filmaking. Dorothy stepped out of the box and left for Europe.
The later part of her silent career she made several films for Herbert Wilcox. Most notable of which was the 1926 film Nell Gwyn. Nell Gwyn was distributed in the United States by Paramount Pictures. Nell was a great success. The follow up, Madame Pompadour, even according to Dorothy herself, was not.