"Why didn't the all those Star Destroyers simply wipe out the last of the rebals? I don't want an answer like because the movie needed to end. A logical reason of how the rebals survived that battle or much less won it."

That's what I just gave you. Because the Emperor's influence was what held the Imperial forces together. They relied on his influence to strengthen their minds and, to some degree, control their will and tell them what to do. With his death their minds were suddenly released and they were confused and lost. So they would have panicked and fled. This is just a theory but it still answers that question, so why are you asking it again? Don't ask if you aren't going to bother reading the response.