Why should the Mobs be subject to the same rules as players?
Honestly?
If you went head to head with your build at your level but it was a computer controlled Mob you *should* win. The only reason you wouldn't is because you're bad at using your character's build. The computer can't "think outside the box". It can't react in realistic intelligent ways and it can't learn.
So unless you want a game that offers Zero challenge you need to learn to accept the fact that the computer can do things you can't.