I'm not quite sure that it could work that way. I think modern tankbusters are designed with flat mitigation in mind, the damage might scale too high as to oneshot a WAR even with their increased max HP, they could adjust it, but it's probably a fine line between making either options too strong. Also making WAR a pure HP tank would cause them to run into issues with bleed applying busters, they could heal back up, but they're also taking the max potency of bleed because they'd have no flat % mitigation. The idea of diversifying the different types of tank mitigation is something that could be interesting though.
By crit busters, I meant the mini-busters that have no telegraph. Those can crit and those can have autos queue up immediately after, tanks can always survive it but it does spike HP downwards randomly. I assume those are the types of issues you find would happen if returning crits to bosses.
