It is more because we know how to counter them that we do not categorize them as ''nightmares''

Give a sword to the hero, he's going to wipe an army for you.
Give the sword to a simple farmer, he's just going to cower away from the opponent.
...

My personal way to see it, I am currently going through a stressful waking life at the moment, and having those ''nightmares'' from time to time.