What would be the benefit of being able to identify the propaganda, practically speaking. I get being principales against it, but are there any big ballot measures I missed? I have no ability to impact the war, why does it matter if I want to rah rah for the invaded a bit?

If you're reading about the war for entertainment's sake, there's no benefit to being able to identify propaganda. If anything, propaganda makes everything more entertaining.

In my case, I have real-life interests, friends, and family involved and the reality of what's happening and the eventual outcomes impact my life in significant ways.

Imagine if the USG had this power in the 60s and 70s as draught dodgers and war protestors sought to provide an alternative perspective. With this technology and todays psyche, they would have been buried and labeled as foreign agents and bits and what have you. People cannot lose sight of that. We need dissent, even when we're right.

What makes you think this didn’t happen? It seems to me that the 60s and 70s were full of this.

It did, but due to the limitations of technology it was not pervasive and did not have control over people's psyche. It did not control students, colleges and libraries, even private companies the way it does today. Not by a long shot.