Do harder difficulties reduce your resistances? [duplicate]
Solution 1:
In Diablo 3, resistances work like Armor. It reduces damage from an element by a flat amount. As you get to higher levels, the amount that gets reduced from same level monsters is reduced. So 90 resist against a level 1 monster will reduce a lot more damage than 90 resist against a level 50 monster.
So, to answer your question, no, higher difficulties do not reduce your resistances directly. Enemies are higher level, and therefore, your resistances are less effective.