It applies to you dear reader, yes you, not u/baggachipz.. YOU.
I am also not immune, I believe myself to be, constantly. My worldview is truth and I am "open to other ideas"- yet I have very obviously anchored myself to things the first time I hear of them, despite actively making steps to try to see all angles and explain away facts with alternative theories. (which is exhausting) I definitely believe what someone wants me to believe.
It's plain, it's obvious, and yet it continually happens. It's only with a decade of distance that I even realise what had happened.
And people call me "balanced" and "intelligent", theoretically I have more tools to deal with this than the majority of the population.
Yet... I am not immune to propaganda.