I noticed the same thing on my wizard in the level 80-100 range I just couldn't hunt solo but after being boosted to 120+ and getting grand kit things became much easier but for my new warrior today I had the same issue yet again.
Warrior = level 91 in full level 90 kit
Recommended Caves:
Zuma Dungeon - level 92 - way too hard the most kill me in seconds
Svaltus Cave - level 86 - also way too hard
Fox Path - level 80 - can just about kill 2 mobs here but killing at that rate its way too slow leveling.
I tried going to the cave below fox path but unfortunately the exp penalty was too high and the mobs were only giving double digit exp.
It seems like the game gets much easier in the 120+ range but the lower levels are a real struggle which shouldn't be the case, if you are wearing an entire kit for your level range then you should be able to hunt the recommended caves without issue.
Warrior = level 91 in full level 90 kit
Recommended Caves:
Zuma Dungeon - level 92 - way too hard the most kill me in seconds
Svaltus Cave - level 86 - also way too hard
Fox Path - level 80 - can just about kill 2 mobs here but killing at that rate its way too slow leveling.
I tried going to the cave below fox path but unfortunately the exp penalty was too high and the mobs were only giving double digit exp.
It seems like the game gets much easier in the 120+ range but the lower levels are a real struggle which shouldn't be the case, if you are wearing an entire kit for your level range then you should be able to hunt the recommended caves without issue.