That is the way that the devs described her, so no, that’s just not true. That is what YOU want her to be. But she is in fact, a tank/support hybrid.
The devs even suggested placing her in the off-tank position. She is an off-tank AND an off-healer. And her current power balance reflects that.
She competes with other tanks by creating space rather than being durable or mitigating damage for her team. Because she is such a large threat in the melee range, you will not enter that area lightly. And because you won’t enter that area lightly, the rest of the backline has room to breathe.
Unlike other off-tanks though she is mostly supposed to enable healers rather than DPS, which is why a dive strategy doesn’t work with her creating that space, as it hinges on killing the support first.