I think that it is all myths. The Old Republic story is being told through the lens of history and myth. This tends to amplify the powers, the effects and the visuals because that's what happens when stories are retold. It is more interesting when the Sith can throw around tons of lightning, the Jedi can throw massive boulders and one lone bounty hunter can take on an army on his own with his rocket launcher and flame throwers that can shoot flame 100 feet across. These things probably only happened very rarely and were massive feats that were hard to replicate, but it helped create the myths of this time and these wars and that's what stuck around.