That's not true.
I agree that when you see these "scenarios" where the teacher is like "come at me with this fake knife..." and you're thinking.."fuck man, nobody comes at you with a knife in their hand like that."
But it's the repetition and muscle memory that saves your ass when/if you get in a real fight.
Being able to take a gun from someone with confidence is awesome.
Knowing you can spinning roundhouse kick someone is awesome.
If I had more money, more motivation and less fat, I'd take some kind of martial art along with some sort of Ju Jujitsu for the ground game.
It would absolutely help you in the real world.