State level actors could always do that, not only before widespread literacy ramped up between 1 and 2 centuries ago, not only before the printing press several centuries before that, but for basically all of recorded history — the etymology for "barbarian" goes back at least to Ancient Greek βάρβαρος ("foreign, non-Greek, strange"), which
might be onomatopoeic mimicry of languages-foreign-to-the-Greeks, like going "blah blah" in English. And they (specifically the Athenians) rather famously had Socrates put to death for saying the wrong things. I think both show different aspects of what real (rather than the mere thought terminating cliché of the same name) "political correctness" looked like at the time.
Cryptographically signing the news might be necessary, but it sure won't be sufficient, as your local government can pretty directly tell people who the trustworthy news sources are/which signatures they should trust. You need more than just the technology to solve problems like this.