If you prohibit it then it will only be done secretly by governments and then used against naive populations. At least this way the population can learn how to identify and defend against it.
If we had transparent governance then maybe this wouldn't be a problem.
Why wouldn't people learn to spot it when the government does it? And I don't know if your argument follows - people clearly either don't know or don't care about the rise of Facebook false reporting.
How do people learn better: lots and lots of practice with varying levels of quality and published examples, or against a single powerful adversary that's trying to conceal what they are doing?
If we had transparent governance then maybe this wouldn't be a problem.