I have noticed that. I'm still level 72 because mobs aren't giving off good enough exp like they used to... I can kill small bosses though.
When you reach 90 you will miss the 72 lvl times. There are still plenty of mobs with a lvl higher than yours. Druid grove is a perfect spot for you with white wisps vulnerable to natural magic and druid-casters. You can solo up to two of them at a time, just remember to keep each on vines and use embrace to stay alive. Lvling goes quickly till 81 or so then it goes slower and slower.
... And if you reach about lvl 80 and you do it right a druid can solo any mini boss in stone.
Hm... can you really solo any mini boss in stone without a ton of pots? I would like to see your amount of 6 star kills.