if the problem is just for new players, just restrict the joining options (to join realm with low player count) only for them at the start. let older players do what they want as it is right now. if the realm count in a continent is lower i think you will face another problem. conflict in BT is caused by 2 small realms because there are only few people in them, its easier to convince/make decision for the realm with 10 people than 20 people. smaller realms are more flexible. just giving out some ideas 
This is actually a great solution. Simply don't let new accounts with less than, say 60 days of game time, join realms with less than 11 nobles.
Although I am for roguing realms with less than 10 players if they maintain that state for 60 days too.
