What if the state itself propagates those "harmful information"? It is a mistake to think that fake news are created spontaneously and that an intervention from above can fix the problem, given that it is plausible to think that they are, in fact, propagated by our media, politicians and state agents.

Also, I'd like to highlight that: 1) Putin has risen to power well before the existence of Internet fake news. Complex factors justify his political existence: economic depression of the country in the 90s; religion; the support of Russian oligarchs; fear of political instability. To say that they were successful in Russia is an oversimplification. 2) They did, however, play a big role in the 2016 US elections :-)