Because people are fucking stupid.

B/c he knows that he does not mean it, and his base knows that he does not mean it, but it still manages to communicate something regardless - "they bad".

Humanity today is genetically identical to those in ancient Greece, and many of us have spent less time schooling ourselves about how to e.g. avoid frauds than many of them did back then. ergo, "argument by authority" still works for us, as perhaps it did for them back then as well.

Your presupposition seems to be that humanity should somehow get better over time? At least it seems to relate to a common humanist theme, but if we want to get better, it is going to require effort on our part to make that happen. (apparently, having access to the entire repository of human knowledge at our fingertips is not sufficient, for those who cannot be bothered to learn from it - either by reading or just sitting passively as videos with pwetty graphics do all the work of spelling it all out for us, yet still that is less fun & engaging to people who would rather watch shiny motor vehicles with ads on them drive round & round in circles)

Republicans are dumber than dogshit.