SE concern about HP Inflation doesn't make sense with existing tank gear

[Reynhart]

Say from item level 320 to 340 the devs decide HP is increasing too quickly, they can reduce the amount gained from 340 to 360. If attack power is tied to VIT then that also screws attack power and requires a change to the AP formula (which is sloppy, like constantly tweaking enmity modifiers)

But with the recent change, they simply ensure that future accessories won't increase damage at all (on the "main stat" part), so attack power is screwed anyway.
It would have made more sense to talk about "Tank damage inflation", in the sense that increasing HP more and more would also increase damage a lot.

[Brannigan]

But with the recent change, they simply ensure that future accessories won't increase damage at all (on the "main stat" part), so attack power is screwed anyway.

This is irrelevant. The point is to have HP and AP isolated from each other so that they can adjust HP values without affecting AP. Even with .45Vit/.45Str they could do that by adjusting the Vit:HP formula, but the problem is that affects people of ALL gear levels. Maybe they just want item level 400 tanks to be at a certain HP value, but are fine with item level 350 HP. How do they change that? By changing the amount of Vit on the i400 gear. The problem with that is that it throws off their projections for tank attack power at that ilvl (if you get AP from Vit), which they might have been fine with before. When all of your AP is on strength, they can tweak tank HP without having any impact on their damage dealt.

2.x was just like how it is now

The stuff you're posting here is replying to something I didn't write. I know what tanks did with their accessories in 2.0 - I'm talking about the Vitality-to-Strength ratio on armor as it relates to increasing item level through the expansion. I don't remember the exact numbers, but in Heavensward an item level 190 body had something close to 5% more vitality than strength, but by item level 240 that had increased to 12% more vitality than strength.

[Kitfox]

The point is to have HP and AP isolated from each other so that they can adjust HP values without affecting AP.

This guy gets it.

Furthermore:

It's a balancing problem.

Increasing tank DPS through VIT has these possible side-effects:
-Tank eHP is increased in comparison to incoming damage
-Non-tank eHP is reduced if tank eHP is balanced by increasing incoming damage

Likewise, reducing tank DPS through VIT has the opposite side-effects:
-Tank eHP is reduced in comparison to incoming damage
-Non-tank eHP is increased if tank eHP is balanced by reducing incoming damage