But that's really, really BAD.
The quote I used is from a marketeer, but it is not far from the truth when it comes to politics. And I personally believe that it is more about gut feelings, rather than beliefs, though those exist as well. Most people do not have the time or desire for deep analysis of complex issues. They rely on headlines, common sense and gut feeling. And stereotypes (which exist for a reason). Now, with fake news all over, whether as fake fake news or really fake news (and precisely because they can't distinguish them anymore), most people haver resorted to common sense and gut feelings. And stereotypes.
Now, most reasonable people would agree that common sense does not always makes sense, or that stereotypes are not applicable in all cases, or that gut feelings might get it wrong. And yet, most people prefer shortcuts to deep analysis. Then again, even deep analysis does not always produce an actionable result, but mostly ends in a "on one hand, and on the other hand..." type of paralysis.
Sometimes, the Gordian knot parable is the solution. Or the Hercules' stables fable.