In the US the debate about DDT was whether to use it as a pesticide. So the choice was about killing the bald eagles and most of our other birds, or slightly increasing pest control costs for farmers and people with lawns.
Ecosystems are complex enough that we have very little information on all the interactions that could happen. It's more than just a bag of organisms mixed together. A better analogy is the network of files and components loaded up during the boot process. Especially early on, each piece is crucial to what happens next.
We have one weapon way more powerful than DDT. It is called intelligence and knowledge, things like controlling pools of water is way more effective that DDTing everything.
People with lack of intelligence or knowledge wants a magic pill that solves all problems without having to think, but this has an enormous cost. When I eat fish from Ebro Delta I'm eating DDTs thanks to them(they are forbidden but some people continue using them).
Yet people find easier to think of the problem from the other side and think that a bunch powerful people who bend the world to their own interests. It is true, there are those people, their effect is significant, but they are part of the game, they cannot control even themselves and their peers, not even when it would be in their interest (as a group).
