That's pretty much how I assumed it would work, though I think they're doing some leveling out of things like they do when you go back to do patrols and the level 6 enemies still take a little time to kill. It's not a linear, static line…the damage scales somewhat. It's been explained better elsewhere, but that's what I think they did instead of making it all about having the highest level, weapon damage, and armor/defense ratings. I think it should just be closer to what you're describing with the ?? level guys being impossible to take on unless you've leveled up enough.