We all know the score.
You get a game with 60 levels, and you start in a zone for levels 1-5, then move on to another zone for levels 6-10, etc., etc.
You can only play in 8.33% of the game world at any one time. Practically speaking, at any rate.
Once you reach level 60, you are pretty much stuck doing the same content until the game releases new content for levels 61-65.
And at that point, you are limited to less than 12% of the world to get any practical benefits from.
And with each new addition to game content, your limited to even a smaller percentage.
By level 80, you are limited to 6.25% of the game world.
Is that a good thing?
(Hint, when you run out of levels, you run out of game.)
I've made two prior posts that relate to this in overall game design.
and After Max Level:https://forums.mmorpg.com/discussion/481646/after-max-level/p1