If people try to exploit the rule to gain an advantage they need to be dealt with on a case-by-case basis. There's not enough people to justify the rule, hell, even when the server was full almost all the time you could hardly justify it.
It's REALLY easy (as in laughably easy) to identify unique users on a single address with the right tools, it should be even easier with the FLHook magic people managed to do when I played the game, to say nothing of the way it is now.