Quote Originally Posted by Jpec07 View Post
I will say it again (and I'll edit the original post to include this):

Killing a mob faster is only viable as mitigation if the damage prevented is greater than the damage that would have been prevented by instead passively mitigating it. Killing a mob faster to save .3% damage by stacking Crit is not viable as mitigation if a full Parry build would have saved you .5% incoming damage.

I'll need to look at some parses later to determine how much damage a tank can save by killing a mob faster versus wearing full Fending, but I have a very hard time believing that tank DPS can have such an effect on the rate at which mobs and bosses die as to make Crit, Skill Speed, or Det more worthwhile than Parry for mitigation.
In regards to dps/mitigation synergy it isn't only just "killing the mob faster" that makes dps stats more viable, while that does help you also need to consider that 2 of the tanks are built in a manner that have dps/mitigation synergy. Meaning they can turn outgoing damage into HP recovery, sometimes at very substantial rates. In regards to secondaries specifically, at any given ilvl you will have static amount of secondary points available. This is known in the community as the "stat budget" of an item. Within that budget there are relative caps for each secondary in regards to SE's decision and the "weight" of the stat. So stacking parry means sacrificing another stat. Due to the nature of dps and mitigation not being mutually exclusive in practice and design of the tank classes, but only in actual stat budgeting, taking damage stats not only allows you to kill the enemy faster but also achieve greater utilization of the abilities that synergize with dps stats.

Now there are ways they could fix parry as a stat to alter the balance here, but in regards to it's very low stacking rate and limited utilization, along with the healing and tank meta it becomes more advantageous to take another stat if possible in it's place. This doesn't mean parry is useless per se, just that there are other stats available that will achieve greater mitigation in it place.

Also I don't think your question or inquiry is unreasonable at all. SE doesn't make these things very obvious and in some cases makes very questionable decision in regards to stats specifically involving tanks. If you would like to see some hard scientific data on the issue I would check out the FFXIV reddit forums and do a search on parry stats or stat weights for tanks. There is some pretty comprehensive research on the issue that has been done by the raiding community if you are interested in that type of thing.