That's all fine and dandy if th emiddle of your line is solid. Ours isn't so our Lineback are constantly filling middle gaps. They are not available to contin IMO. Our Dends are usually set pretty wide. While I will somewhat agree that containment shouldn't be the only priority, our Dends constantly run by linebackers. If there is a sweep run toward you you absolutely cannot let it get outside of you. You have to make them cut it up and let one of the backers fill.
I'm not sure what defense you are watching, but it isn't the defense that ISU runs unless you are going back to the old Okie 5-2 from the 70's. In a 4-3, the DE's do not line up wide. Especially the strong side DE as he lines up inside the TE on the OT. The back side DE also lines up on the OT. Once again, he is looking at the C gap while holding his ground and not getting pushed out wide to open up the B gap. He is usually only checking the D gap for plays like boots and reverses.
I agree that the player who has force responsibility can not let the play get outside of them. The issue is that the force is almost never the DE as they have other more important responsibilities. The force is either a LB or S. If anyone has ever had a coach tell them otherwise, I would hope that they were simply behind the times and still trying to run either a 5-2 or a 5-3 defense.