Elemental Equilibrium all 3 elements.

Hi.
Today I noticed that EE is work weird.
When I wield dagger with added 3 different elements damage to attacks, and cycloning through monster I realize that increase monsters resistance to all 3 elements.
Is that OK ?
I always thought that should decrease resistance to all elements.

"

If you hit an enemy with two different elements at the same time it will give -50% Resistance to third element and +25% to both elements used. A hit carrying all three elements types will give +25% to all elemental Resistances.[1]

From the wiki.

To put it simply 'when you hit an enemy, they gain 25% resist to all elements present in the hit and lose 50% to all elements not present'.