Seriously, some of the comments are brilliant. Remember, there was a time when you yourself was a 'newbie' and started a league. If there would have been restrictions then?
One league per member is the way to go. We can have something like premier leagues of top 8/9/10 nations. One champions league which turn wise each league manager will run. We can actually have proper time periods in which a particular thing happens. Something which looks neat and professional. This way we can have the other leagues (non-nations) running as well without there being too many leagues.
Surely a long process but, if once put into action it can do wonders. Since there isn't going to be any PCCL or something like that, we can make these leagues more enjoyable rather than pain.