I never said it was perfect at all. I only used it as example to explain how you need to keep players engaged for them to stay. The grind didn't end up breaking the player and making them quit at higher levels. The obvious problem with this is that levels 1-50/60 are way too fast and it's just a blur.
In order for the higher levels to not be ridiculously slow, the early levels had to be ridiculously fast. This is because Xor was using an exp rate that got slower and slower and slower every level like on Official. To end smoothly it had to overcompensate at the beginning with its 25x exp rate.
What PWI needs to do over here is smooth out the leveling experience, and maybe lower the total exp required for 99 overall. Back on the old Rohan you'd get to 35 in 1 day, 50 in 2. 50-60 would take 2 days, 60-70 about 4, 70-80 about 2 weeks.
Levels 60+ could be sped up at the cost of slowing down 1-59 a little bit. 1-59 doesn't need to go by in a week, and 60-99 shouldn't take 8 months.