I blame it more on the sheer amount of them they throw at them.
It reminds me of some Goldeneye levels on the harder difficulties that had infinite spawning enemies. I always hated that about the game. It was a spy game and I thought you should be able to eliminate every enemy in the level and wander around freely to finish the objectives.
You could in some cases. I had a blast in that one Goldeneye level where you had to escape from the jail cell and take out the facility just luring enemies into my cell one-by-one so I could take them out and take all their guns. Then I'd just tour around the facility blowing things up with no one left to stop me, even on the highest difficulty level.
EDIT: Incidentally, I was window-browsing my local Gamestop today and they still had one copy left of the Conduit Special Edition. Damn, I almost bought it just to have a copy without the ****ty cover art...but I must resist...Batman's only 2 months away, and my backlog's insane as it is...