This is a major problem in one of my games. I do not know what Bytro's policy is on this but it seems as though they like to turn a blind eye to it at best.
I'm currently in a 500 player game where one country in particular has 828 provinces on day 40. The next biggest player, an ally of his, has 271. This guy had control of about half of South America before day 20, which shouldn't be possible without multi-accounts, much less the extremely generous use of goldmark. I know goldmark and high command (which the player in question is also a member of) helps bytro's revenue but this is out of hand. Several players (myself included) realized and have reported him but no action at all has been taken and it makes me think that the overall player experience is not a priority here, unless of course, you have ridiculous amounts of money to throw at the game.