This is false. There is a way that you can finish the starting zone before lvl 10. Don't use any boas. and always kill the lowest level creatures possible dont kill any more than you need to. Try and do it while dead and in a party with a firiend. There are multiple ways it just takes a while sometimes to get it right.I don't know if this is still true for 5.0, but here is a blue post about it.
When can worgen leave Gilneas? - MMO-Champion BlueTracker