They don't usually come with the Rok-landing type of WAAAUGH though, because they can't make it to the surface intact. It was more-or-less universally agreed, even if by omission, that bringing along a Gargant/Titan-sized unit would wreak unimaginable havoc and likely singlehandedly win the war, because nothing in the Starcraft universe even approaches that scale of land unit. An Omegalisk miiiiight go head-to-head with a Gargant, but that's pretty much it, and they're so rare as to be practically nonexistent.