Once you played the game for a long time who really wants to lvl up all over again 
I have multiple toons for each build , cause I can’t really bother respeccing all my paragons every time I want to play a different build.
I just hit pits with a friend and I’m 60 in less then 10 minutes.
Some of the greatest rpg/arpg no one plays them for the quest line , the boss encounters or the leveling experience.
It’s all about competing.
If you don’t get people competing and you don’t have an end game what exactly are you doing ?
You running in circles lol ….that’s what diablo is.
No joke ……I can log in right now and in less then 30 minutes I have a level 60 paragon 296 fully decked out with all the mythical and gear I need and ready to push a pit 95.
That’s Diablo 4 state atm.