IB: amazing horde waveclear. Ulti can save living teammates while taunting and creating space when cast while he himself is extremely durable
FK: damage resistance aura (admittedly small radius that needs major buff) w +1 shield for team and low cool down cc ulti that can perma stun bosses or create space for teammates/get to downed teammates with ease.
Zealot? Unchained?: both are the tankiest of their character careers but both are still pseudo dps classes. Unchained ulti can create space for teammates or to cc as she resses.
HM: a stamina Regen aura. This is something that is wasted 90% of the time as most players don’t sit around stamina starved. Outside of this her utility to team is nil while they are all alive.
I don’t think all tanks are useless. A good IB on a team that can effectively neutralize his weakest area of special killing from range (assuming cannon or pistols) is an invaluable asset. I DO think a tank career that kills specials worse than her ranged career subclass and kills elites and bosses worse than her melee career subclass without really succeeding in some way those two classes fail (other than to be able to live longer when everything goes downhill) is LESS USEFUL hence her tier.
As a disclaimer I think HM is a fun class and I have had many very solid HM players on my team clutch runs and contribute to the success of the team.
All careers are viable in the hands of a skilled player. For example, I’ve been pleasantly surprised by the utility of battle wizard with conflagration staff. It’s extremely tactile to redirect hordes, perma stun patrols and stagger elites. Special and boss killing is a relative weak point. While her ability to block until ventilate for a very rapid sequence full charge conflagration attack is very strong. Her ulti gives her an easy out and can be aimed at a down teammate to cc what killed them for a res. (Hold F down then aim the circle where you want to go don’t just press it)