If you can't understand that some DOTS, particularly stacked DOTS, can outdamage the regeneration of many regen forms, that cannot outdamage the max damage reduction of a retracted (or unretracted) armadillo + slow, we can't help you.
Dillo partially substitutes for a regen form due entirely to the fact that for every stacked bleeding and disease effect you have on, you are taking grazes, and healing at the normal slowed rate. Regen forms require time to heal as well, and while they get health by the pulse and by the tick, regen forms rarely pair with enough damage reduction to make, say, healing in between bouncing between mobs (but no ability to create distance) possible.