Not totally true, based on everything I've heard FD is a pile of crap that chugs, crashes, and can eat your file. Mind you that hasn't stopped it from remaining on top for now, but I would not be surprised if it stops being the default in the next 5-10 years.
From a cursory read of its website, it looks like a pre-internet app, basically a glorified text editor. There are zero network-enabled features. The only groupware-oriented feature is coloring pages differently if someone else edits the document. There is plenty of scope for disruption here.
The only "key feature" they have is that everyone in Hollywood uses FD. They say so themselves on their website! The "Key features" screen does not list any actual feature, it's just a list of variations on the concept that "everyone in Hollywood uses FD". In that sense, the main challenge is clearly political rather than technological.
Colored pages isn't about group editing per se, it is an artifact of not being able to change page numbers to avoid screwing with the shooting script. Instead you have like page 5 and then 5 red that is the extra page.
