As they run into information that runs counter to their "reality" this article works to explain that it isn't their fault - they are just being fooled by cunning disinformation that appears convincing and very believable. So, they should realize that any doubts that may crop up are part of the devious plan to turn them away from what is both good and truthful.
So, what I don't understand is how you can read this as a lefty and still be a lefty.
My opinion:
It tries to alleviate the cognitive dissonance.
As they run into information that runs counter to their "reality" this article works to explain that it isn't their fault - they are just being fooled by cunning disinformation that appears convincing and very believable. So, they should realize that any doubts that may crop up are part of the devious plan to turn them away from what is both good and truthful.