To all you people arguing about there being a million Pureblood Sith, remember that while yes it will look like that. Storywise, it will still be very rare. Because even in MMO's, storywise you are part of a small elite group capable of doing everything you are.
For example, did 500 Sith go and steal Revan's mask or kill Darth Thanaton? No, just you playing through the story, and that other guy also playing through the story.
Story / lore wise. Still rare.