There has to be a vacuum (below atom) or why would the air go in (there would be equal pressure each side). The intake flap restricts fresh air and so increases the draw on exhaust gas. Yes landrover and many others used intake flaps they were also used when we had vacuum governors. As normal there is a lot of these systems / controls have been around for years and just used differently and more precisely.
Egr can also be used to warm the cooling system as well as the air temp in the cylinders.