It is difficult to fight bosses when people that are farming XP keep teleporting. Not everyone speaks the same language and can understand that you want to fight the boss.

People get stuck on a level and can't progress with a decent party which is not fair for those that can clear the map, but not solo bosses. This will help people do quests and play the game with everyone else.

One possible idea

Have the maps for XP farming have no bosses and purely for XP and create an arena like place for all the new bosses.

For elite put mobs and bosses together.