I don't think people are too stupid to discern the truth.
I think a lot of people are too overwhelmed by the minutia of navigating their own stressful lives to handle a deluge of lies designed by expert propagandists to be easier and more appealing for them to consume than the truth.
The difference is that these aren't leaflets being dropped from the sky on a village of a few hundred people. These lies that span our entire country and they are coming from people that have access to analytical data which allows them to observe how their lie is being received so that they can refine their messaging immediately.
There has never been a propaganda delivery system like this before. History isn't going to be useful here.