You didn't find it difficult because you were a king.
Leadership is not just as it was in earlier versions. Try being a leader in an alliance as a governor. Then try convincing a king he should remove one of his active but non-communicating governors, who is of course giving tributes if he's smart at all. If he doesn't want to, you only have the option as a leader to remove the king and ALL of his governors from your alliance...Great. Or at best, make someone king who will then have to fight with the previous king. Depending on what the alliance and the people are like, it might not go so well. Leadership should always be able to remove someone from the alliance, whether that removes him from the kingdom or not.