Shouldn't Rupture be Universal damage?

Title says it all, HP Removal has unique interactions with items like Healing Salves and Clarities in that it doesn't cancel them. Universal Damage (like Doom) and inflated damage values to keep the same functional damage would have achieved the same result with less bugs to fix (or were they intended?).

Universal damage is reduced by magic resistance whereas hp removal is essentially pure damage but it can target magic immune units. So if rupture at lvl 3 is targeted at a unit and it moves 600 units. it would do 600*.6 damage. If it was universal it would do (600*.6)*.75(provded the unit has the base 25% magic resistance). Its a buff that makes him viable against melee carries that need to chase.

HP removal is supposed to deal damage to invulnerable units. such as morphling waveform and storm spirit's ball lightning. If they wanted pure damage that goes through magic immunity but doesn't damage invulnerable heroes, they should've called it something else