It's also the static view of the Left. It's funny how they're always touting words like "progress" and "change" but they believe in an ultimately static view of the world. Can't introduce automation because people are paid to do that work, we need to subsidize this obsolete industry, etc, etc. And the worst example of this is their assumption that the economy is a pie of fixed size that never grows.
So it's the same with this stuff. Surely there are many species of plants and animals that have benefit from the way human engineering altered the flow of water. Just tell them bringing back the beavers would endanger some species of snail that currently thrives in manmade reservoirs.