The Division 2 has done this to some extent.
By world tiers, I mean a setting that allows the players to set the difficulty of the overall world. The same way only the Host can choose quests, the host would be able to select a tier for the world.
Tiers could easily be similar to sparrow Tales.
Every 10 levels the tier increases.
Example: Host selects they want their world to be Tier 3.
Give them a loading screen.
Now all enemies within the world are between levels 21-30. Same goes for sparrow tales and so on. The rewards are scaled based of the tier of the world.
Reason:
Lord have mercy on our souls, trying to pinpoint the exact locations where enemies and quests of a specific level can be accessed to fine tune difficulty and the efficiency of grinding the never ending reputation early on is an absolutely abysmal experience.
I love the game, but having to travel to Narnia just for the sake of getting an extra pittance of difficulty or more reputation is not fun. Yes, you've built an absolutely gorgeous world, but I only have so much time to actually enjoy the game.
If you want people to travel around the world, make a resource heatmap. Different areas, different resources.
Other similar suggestions:
#1476107609290313810 message
#1483644003726524667 message