The conversation about “teaching students to think critically” has been taking place for at least twenty years (for example, look up “Proceedings of the 1996 international conference on Learning sciences”; http://dl.acm.org/citation.cfm?id=1161135&picked=prox&cfid=748024299&cftoken=68199815), but still has not moved beyond the initial statement that “we need to teach students to think critically” (for example, look up “International Conference on Learning Sciences; 2016 Proceedings”; https://www.isls.org/icls/2016/).
P.S. Russian (or, for that matter, any other adversary's) intelligence forces saw an opportunity to use Facebook, Twitter, and Google to influence 2016 elections. This whole post has been based on the assumption that American intelligence forces did not see that coming and did not prepare the counter activities. But logically speaking, there are also other versions of the events.
(a) American intelligence forces saw it but was not able to do much about it. Or,
(b) American intelligence forces saw it but decided to do nothing.
Of course, I prefer thinking that the real reason is the state of the general education.
Some links on the matter: