>>25582262I'll agree with you that the playtesters get a lot of undeserved flack. I'm not the one putting the blame on them here, though. It's straight from the L4D1 commentary. Somewhere around either Burger Tank or the pawn shop safe room, I think. You can see where they ended up cutting stuff if you noclip or just hop around as a hunter.
You're right though, about the open-ended levels always ending with a preferred path. It takes extreme level-design skills to make multiple paths with the same level of challenge, so I can't blame custom map makers for not trying harder.