The tanks can survive the stacked stack markers, that’s the bonkers thing, you can survive them with your two minutes and your short CD. Stacked stack markers are basically just a punishment for everyone else. The tanks already do it on M6 simply because nothing else in casual content requires your mitigation, you can just hold them for stacked stack markers
If the only reason people play tanks is because they are immortal then that’s terrible design and shouldn’t be seen as a “well it’s immortality or nobody plays them”, and if we are so desperate to avoid a tank shortage then why aren’t we going crazy to avoid the current healer shortage, instead that’s just seen as a “well nothing we can do”
Other jobs shouldn’t be punished with being forced to watch the tanks solo the boss when situations aren’t necessarily their fault. Even if it is their fault such a bad healer that’s just rude and unfair especially if they are trying to learn. It’s slower, it’s not fun for anyone else and it’s only possible because tanks leverage their massive HP pools. Every time these solos happen the tanks are never actually “good” the games damage just doesn’t scale to how much damage a tank can take. That’s bad design on the tanks part