Yes, but it takes much longer for a horker barb to get that kill count up compared to all S tier builds who can obliterate the whole screen without loosing time to think/spot those elites and then howl and kill more slowly then hork.
yeah and this also
part of the mechanic to spawn them still requires killing density
Ire has a 2% chance to trigger upon elite killing.
Nothing to do with density.
And your "S tier builds" who can "obliterate the whole screen without loosing time to think" will be killing white trash mobs while the horker will just be spotting an actual elite.
All this time you spend killing trash mobs is a waste of time in regards of spawning an Herald.