Already in the past expansion, pure tank raids were quite popular and also successful. With WoW Shadowlands, however, essences and corruption effects fell away, which dramatically lowered the damage done by tanks. Still, a Guardian Druid-only group could now successfully master Castle Nathria. Even the healer boss Save the Sun King wasn't much of a challenge - in fact, it was one of the easier bosses.
Tanks can not only take a lot of damage in WoW Shadowlands, but they can also keep themselves alive quite nicely thanks to self-healing. It's only in terms of damage dealt that they are significantly behind. That didn't stop Dragon_Bjorn and his colleagues from taking a raid of Guardian Druids to Castle Nathria to take on the ten bosses. With a dozen or so Bears, the party slashed through the ten bosses more or less effortlessly.
Already in BfA we saw several such pure tank groups. Back then, however, the frontline fighters could still fall back on essences and corruption effects, which increased their DpS, sometimes drastically. In Shadowlands, this is no longer the case, resulting in tanks doing significantly less damage than DpS playstyles. However, since Druids can take a beating and thus ignore one mechanic or another, they even managed to successfully get past DpS checks like Silt Fist - albeit by an extremely narrow margin.
They even managed to defeat Save the Sun King, the healer boss in Castle Nathria. It's here that you'd think tanks would have a problem. However, thanks to Restoration Affinity, Heart of the Wild, and Convocation of Spirits, they healed the boss up faster than most groups.
Things got a little tricky at the final boss, where you have to kill adds on the outer platforms that melee fighters can't get to. However, thanks to balance affinity and Heart of the Wild, the party was able to muster enough ranged damage to defeat the outer cabalists reasonably quickly and still succeed. The rest was a piece of cake for the tough Druid tanks.
In the near future, the Druid group will try their hand at heroic mode, which should then be extremely difficult in some places. We are curious to see when the first tank-only group will be able to successfully conquer this difficulty level.