Well what you do have more on the official server is this: People who love to blow up less experienced players and gloat about it, people who make fun of less experienced players, who like to humiliate less experienced players, who like to make other people angry, who like to make other people angry enough to violate rules.
If anything is siphoning anyone from other freelancer servers, its the official discoverygc server. Not because it's better, but simply because it has the highest population. Herding instinct. That's really what kept the official server running with high population for the past decade. People were always here for the high population, and not for how the server was run, and not for the "quality" of the population either.
EDIT: Come to think of it, there are occasionally people as described in the first paragraph who pop up on the low population servers, but if the admins let them stay there, they tend to kill off the server activity withing a few months (thinking of Doj's and Alex's stay on Disco UK, and Vicious&co on disco PTC).
User was banned for: Karlotta alt
Time left: (Permanent)