[Poruku]

In my opinion, if in the lategame people are expected to have at least 20% resist to all elements, then elemental damage should do about 25% more damage than anything else. That means you get slightly raped if you have 0% rez, but you still take no damage with guard and evasion and 50% resist and all the fun things that exist to deal with this. If you just give them more damage, then you would need to balance out your resists in order to not get raped, so there will always be able to deal reasonable damage.

In the game Path of Exile, elemental resistances in the lategame are expected to ALWAYS be at 75%, which is the maximum. As a result, elemental damage from mobs deal about 4x more damage, but player elemental damage has ways to pierce high resistance mobs. This normalises the damage, since it means you can never face an enemy which will mitigate more than about 25% than your damage.

In the case where the enemy has 0% resistance, you can also go into the negative. This is equivalent to less of an advantage than when you face a high-resist enemy. let's do math.

100 damage

75% > 25% = from 25 to 75

triple damage

25% > -25% = from 75 to 125

1.67x damage

A good balance for sig might be around 20% pierce resist for a chosen element. This would make it viable for characters who use a single element for IC reasons.

TLDR if you base your strategy around something, you need a way to make that strategy reliable against the things that counter it, even if that means it still gets countered slightly.