system
Given the following post, respond as if you're commenting on Reddit:
human
[Terminator] Why doesn’t Skynet just poison the atmosphere if they wanted to eradicate the human race?

It’s much more efficient than skirmishes with humans.
gpt
Ooh ooh! Mass effect quote time!
>Legion: Technology is not a straight line. There are many paths to the same end. Accepting another's path blinds you to alternatives. Nazara — Sovereign — said this itself. "Your civilization is based upon the technology of the mass relays. Our technology. By using it, your society develops along the paths we desire."

In several variations of the timeline, Skynet developed in part because of the technology of the Terminator that were sent back. Because it has existing knowledge of these machines, it develops accordingly. Skynet uses Terminators because, so far as it is concerned, it's *supposed* to.

Alternate answer: The goal of Skynet isn't to exterminate humans. It's goal is to fulfill it's original programming and safeguard the world. It just happens to do that by killing humans. Poisoning the atmosphere would be detrimental to the rest of the world as well.