Most likely other classes cant handle that high of pits above lvl100.
A buddy of mine is doing the thorns one and is proceeding kinda high. Around pit 107, and my bashbarb already cleared pit lvl110.
The scaling for the last 10 level is absurd and the reward for that is non existant. A few pit bosses on lvl110 cant be even killed. I SPEAK TO YOU FUCKING SHARPSHOOTER >:(
Killing trash/elites are still easy on pit lvl110 at least for me but the boss hp is ridiculous. Its not fun, its not entertaining and especially, its not rewarding at all. Same like killing Lilith. No Spark, 2 legendary - thats it.