Tanks, please use strength gear.. :(

[Sapphidia]

Again, wearing STR jewelry doesn't prevent the healer from DPSing at all if you play properly.

This is not objectively true. It's true for reasonably high gear levels, but if a tank is undergeared and has very low base vitality then even popping cooldowns properly a healer might struggle to output a full dps rotation before having to turn CS off and heal.

You're not taking into account the way Cleric Stance works. Turn it on, and you have 5+ seconds where you basically -cannot- heal and can only do a DPS rotation. Tanks need enough vitality to be able to survive a full length rotation of casts before needing a single heal, and low geared tanks often need healing more frequently if wearing strength gear, even if popping cooldowns properly.

Take Scholars. Their usual, optimal aoe DPS rotation is Cleric Stance -> Shadowflare -> Bio 2 -> Miasma -> Bio -> Bane -> run up and Miasma 2. (they can then tab-spam Aero on each mob if healing isnt needed). That's a lot of global cooldowns on dps. If a tank can survive 5 seconds from full health to dead then they can only get a couple of casts off before having to swap out to heal. If a tank can survive 7 seconds they can get a full three-dot Bane. If they can survive 10 seconds they can get the entire rotation off. If they survive 12-15 seconds they can get aeros off.

Sure, a tank with 17k health from 190/200 gear would easily be able to survive long enough on big pulls, but a new tank with 13k health wearing strength gear would survive only about 2/3 as long (due to 70% health plus lower defenses). In these cases, yes, having vitality accessories can increase healer DPS by increasing the number of casts a healer can get off in their rotation.

It's situational and gear dependant, not an objective truth. Healers can always do SOME dps, but vitality on the tank can increase the length of a rotation at LOWER gear levels at least.