If we find a world is being artificially prolonged simply to flag farm then we can remove the possibility of gaining new flags, it does apply to all current & future worlds including casuals, as to how is it determined whether someone is competitive or not? A world with no conquers but players simply producing & killing nobles just to gain flags is one good indicator.
The major point here is, it will have little to no effect on the majority of worlds, it is simply an option available now to prevent potential future abuse.