One comment on the notion that these spread quickly because of "hope and positivity".

I think this is only looking at one side of the coin. What I think they mean to hone in on is the inherent advantage that sensationalism has in social media. Sensationalism is attractive in social media because it gives users social capital in terms of likes/shares/etc. (Or STEEM, of course.)

Other than that small nitpick, I think this is all right on.