Yeah well the dwemer thought too hard one day and just fucking erased themselves from the godhead. Can't do that if you don't even question how shouting dragon words changes reality or why only those with dragon blood even attempt to say dragon words or what happened between talos and a cat to produce a khajit dragonborn several centuries later.
Dragon born is basically just easy mode for learning shouts. Ulfric probably only knew one shout and I’ve always assumed it was something like a raw power of the Thuum rather than something like a fire shout to be “shouted apart”
For most of users it just emits violence from their mouths, which seems pretty redundant, since it's something Nords didn't ever have any problem with using their hands.