I view what players are doing with ES as a kind of loophole where the developers forgot to close, which was exacerbated by bad itemization.
It might as well be the VISION, who knows, but it's definitely not freeform gameplay that POE1 provides, where you can be both a zhp zoom-zoom character or uber tank that is essentially unkillable by almost every attack (i.e. my
https://pobb.in/ZtpEcuNOb5k2 latest SSF character). It was one of the biggest allures of PoE1 as compared to D3 or some other games - 'play as you want instead of play as we want'. Also, the trade will always push the community towards zoom-zoom, "press one button, whole screen dies" builds because they allow you to farm the maximum amount of currency / gear (and in poe2 this is compounded by the fact how rarity works atm).
Its a bit tricky because high percentage reduction actually gets increasing returns from a lot of damage, and you get higher returns the closer you are to hardcap
I'd say they just mindlessly copied the old poe1 formula without taking into account that you have more% aura in poe1 (which was nerfed recently) and the other defensive layers that are dependant or tied to armour (molten armour, aegis procs or other things).