It isn't just that people aren't taught thinking skills, it's that people are actively attacked and coerced into suppressing that kind of thinking style. Going through normal public schooling systems most people are taught during key developmental phases that questioning the world around you causes punishment. If it isn't your parents, it's your teachers or the government constantly shoving stupid thought-suppressing ideas in your head. During these phases your immune system learns to associate free thinking with abuse and pain. When you are an adult it becomes very difficult to undo this. An adult who gets very emotional when their beliefs are questioned likely got abuse and punishment when they questioned the beliefs of those around them in youth.