The simple explanation is incompetence: the ratio of false negatives is too high, so everyone has a story of being rejected from jobs they could perfectly fulfil. The ratio of false positives is also high, so jobs remain open for longer they should.

I recently met the CTO of a unicorn in a social function, and they urged me to apply, he would fast track. I interviewed there before, got an offer but decided to go somewhere else. Even with a face-to-face invitation from the CTO and obviously having passed an interview in the past, they rejected me.

There is no end to incompetence in modern business.