Not that I want to justify abusing the stacking tank debuff mechanic, but there's only so much you can do with multiple tanks in small group raids. Damage split (Hydra), armor debuffs, adds to tank - and that's pretty much it. Sure, you can design crazy stuff like the
Netherspite encounter or proper council-type fights like WoW's
ODS but... It takes proper designers and time which SE doesn't have it seems. I have no idea why they can't modify a few bits here and there, fine-tuning some fights to only have one tank (and allowing stuff like
Atramedes encounter), but I guess their whole system is as unflexible as it gets. So unless something changes drastically, we can expect more AoEs, more forced tank-swapping and the like.