> I'm generally afraid of a future where this phenomenon becomes better understood and weaponized.
This phenomena was weaponized over a century ago. The Spanish-American war was largely instigated by propaganda so that William Randolph Hearst could sell more papers ("You furnish the pictures and I'll furnish the war"). Mass communications and mass advertising was critical to developing the mass markets of the early 20th century. Propaganda played a huge part in both World Wars, and was critical to Hitler's rise to head of the Nazi Germany. Orwell's 1984 wasn't speculation about a hypothetical future 35 years off; it was a thinly-veiled allegory of his actual experience writing cultural broadcasts for the BBC during WW2.
The history of modernity is literally the history of getting large bodies of people to think alike, to buy into particular models of reality, and to subsume their individual, family, or tribal interests under broader national interests. That's how we distinguish the "modern" world from "pre-modern" civilizations that we have largely enslaved or exterminated.
On a broader level propaganda and weaponized information dates back to the ancient Romans and Greeks, but the invention of movable type, radio, and TV dramatically accelerated it. Arguably the Internet is reversing that trend by giving a large plurality of voices an audience, but those of us who grew up in the modern era have brains so conditioned to a monopoly of worldviews that we have trouble making sense of it all.