system
Given the following post, respond as if you're commenting on Reddit:
human
[Tomorrow War] SPOILERS

Okay, so *why* draft people in the past to fight in the future instead of sending back all your data to help prepare for the invasion?

At the very least they could've sent info on how to build a more stable time portal so that the past could establish a better connection to the future. And maybe send the specs to make those guns with limitless ammo so they could flood Russia with millions of them in anticipation of the alien arrival.
gpt
The way that they try to take people who they know are due to die means presumably paradoxes are a concern. Since the tech is in its infancy its possible they don't know how much the timeline can be changed or if doing so would be catastrophic. 

But then it turns out it can be so its all fine.