No, they’re not. VDH is noticably stronger, if you play it right. No tank is meant to survive for long on their own, but VDH has plenty of defenses. Spirit Bomb is the offensive build by the way, you can get considerably more survival with a Fiery Brand build, but that’s completely unnecessary for M0 and the keys we will be doing in the next couple of weeks.
So, what makes VDH strong?
They have Spirit Bomb, obviously, which doesn’t heal that much itself, but the Frailty debuff it applies, is a nice boon. Spirit Bombing a big pack and dropping a Decree will heal you quite a bit, and also do a nice amount of damage. They also have Demon Spikes, a good defensive against melee and physical damage. You can - and should - place Fiery Brand on the most dangerous mob of the pack for a sweet 40% damage reduction for 10 seconds (that’s huge!). They have Sigil of Silence for an AoE silence, incredible for interrupting multiple casters.
Imagine a pack with multiple casters, including a dangerous one: you jump in, interrupt the dangerous one, then a few seconds after, Sigil of Silence, interrupting it once more, and when that expires, Sigil of Chains them a few feet away to interrupt again, and if they dare cast again, Sigil of Misery, and if they’re still alive, Fiery Brand the big one. You just nullified an entire caster pack for 10+ seconds. In the meantime, you can have Spirit Bomb popped and Frailty applied, with Immolation Aura healing you, and Decree blowing them up (chains + decree combo is amazing against a caster group). If there’s melee in the group, and you need more defenses than the Frailty & Spirit Bomb healing: Demon Spikes - but chains & misery will help with them too. With the pack mostly rendered harmless, you’re free to use Soul Cleave instead of Spirit Bomb, to reduce the cooldown of Decree, if you have Razelikh’s legendary (which you should with a Kyrian Spirit Bomb build, it’s very, very strong).
For melee heavy packs, or when the sigils and other CDs may not be available, there’s also Fel Devastation, which pops you into Meta for 6 seconds with Demonic after the cast, with all the benefits of that. Fel Devastation also heals for a substantial amount in and of itself, and with Frailty on the pack, even more. If in danger, you can still pop Meta after, or just Sigil of Chains the pack, and Infernal Strike away, and kite.
You don’t need to face-tank everything all the time. If you’re out of defensives, just build threat and get the heck out of there and kite until your defensives are back up. Pulling with pre-casting Decree, then Infernal Strike, Spirit Bomb, Immolation Aura, then Infernal Strike out and leg it with Sigil of Chains / Misery behind - that’s a boat load of initial threat in a short amount of time.
VDH is easily the strongest M+ tank right now, but it only works if you use your abilities to your advantage. Randomly pressing buttons, or popping everything all at the same time will not work out well. You need to know when to use what, which mobs to Brand, which one to interrupt, and so on and so forth. But once you get the hang of it, and you can line up your CDs well, VDH is a monster, even in the Spirit Bomb build.
With a Fiery Brand build, you’re nigh unkillable, but the damage - and thus threat - suffers greatly, so I’d advise against playing that build at this point.