Depends on what you mean by active mitigation.

Rotational abilities that maintain mitigation effects (STR down/INT down) previously existed but are gone because they forced groups to pick certain comps. Short recast cooldowns (Shelltron/RI/TBN/HoS) exist but most damage is focused on either raidwides (non-tank) or tankbusters (invuln -> swap). There isn't much in the way of Living Liquid style fights to test your cleave timings.

If you want to have active mitigation, you need fight design that forces tanks to actively mitigate. You also need invulns to be less powerful than they currently are in relation to content.