They NEVER ask themselves, "Is that plausible?" Nor to they do anything that resembles fact-checking.

There are two underlying reasons for this. One is that public schools, even many of the very good public schools out there, simply don't teach critical thinking. They just want you to parrot back whatever you're fed. Private secular schools are a bit better at teaching critical thinking, buy most parochial schools, especially those run by fundamentalists, completely abhor independent thinking on the part of the students. Home schoolers, ditto.

The second is religion. Even liberal Protestant sects can have an undercurrent of "Believe what we teach, don't question it." And it's a raging river in huge areas of organized religion.

And so young people are told by all the adults around them just to believe. When it comes to some of the pure stupidity that shows up on the internet, they believe that also.

Thus you get people who believe whole-heartedly in the points in the OP, as well as other points made in this thread. Plus, too many people were never, ever going to vote for a woman, not even Mother Teresa, were she alive to run for office. Unfortunately, Hillary Clinton was for a lot of reasons never going to be able to overcome that generic and intense dislike of a woman candidate. Someday some other woman will. I just hope that happens sooner rather than later.