Ok so DRK might be a tank that sacrifices even more base mitigation for a greater self heal, like a polarised version of WAR compared to PLD.

One can already see cons of this style of tanking because it relies on constant uptime to have the same level of 'mitigation' as other tanks get.

PLD's mitigation is almost entirely cooldown-based.
WAR needs to land Inner Beast when it matters.
What's wrong with a tank that relies even more on landing attacks to have the same level of mitigation?