Most popular servers I go on have global ranks.So if people get tired of one server they can go to the next. This may increase squads popularity.
In my opinion I don't think this is a very good idea and I think surge would agree with me. There other ways to do this for example paying for advertisement or adding new gamemodes.
Surge did suggest something similar but I think it was along the lines of you buy a rank and you get a cheaper rank on all the other servers