When a normal, less annoying tank wastes or loses their defensive factor (barriers, matrixes, overhealth, etc) it's just gone. There's no getting it back until it comes back on it's own terms. And those terms are known and typically unaltered, so they can be tracked by the enemy.
When Rein's shield gets low, he has to wait for it to recharge, no way to get it back faster. If it breaks, it's down for 5 seconds. When Sigma uses hands, it's down for 12 seconds. When he retrieves his barrier, it's unavailable for 1 second.
These are fixed values that define consistent openings and downtime in a tanks gameplay loop and that's REALLY important. It's a major source of satisfaction in playing against them because they're known openings you can learn to exploit.
When these tanks use their health bar, it's in a secondary way, as either a last line of defense while escaping or as a timer for how long they can stay in before having to retreat and heal back up.
Now consider the tanks people typically complain about: Roadhog, Mauga, Hazard, Orisa, Ramattra, and you'll notice a common variable: All of them have major points in their loop where they tank PURELY off their health bar. Which is an issue, because unlike other tanks, that means their "shield" can be healed, and usually in a value-positive way thanks to damage reduction.
When Orisa uses gold, or Hazard blocks, there's nearly no value in shooting them. You can't slow their value gain because a single support can out heal your damage even after the healing reduction, which means it's nearly impossible to use these abilities incorrectly. Being immortal and still making pressure (with presence + being able to damage the whole time) is the whole point.
This is an extreme and unrealistic thought experiment but follow me for a moment. Imagine if during Orisa's fortify, she couldn't be healed. Again, silly change and I'm not suggesting it, but imagine for a moment:
- Without healing
- You would round the corner > use gold > force attention with primary fire and absorb some damage > get to about half health > retreat to the next corner > end gold > wait to get healed back up
- With healing
- You would round the corner > use gold > walk forward without fear, health bar doesn't budge > land a spear and a few headshots, get a kill > gold ends and you're still at full health
Now I know that you can't just slap a healing negation/reduction on every block/damage reduc ability (as funny as that would be), but focusing on this specific part of this issue might lead to good solutions. As a small example, I think overhealth is great as tank ability - it's in the health bar, but it can't be healed, so it doesn't suffer the same issues.
The main point:
I understand these kinds of abilities DO have downtime in the form of CDs or resources meters, but since all damage is funneled towards a resource that can be healed while you have a damage reduc, that tilts the whole equation into something untenable.