A lot of people just want to be modest and realistic. They don't like decorating things, telling half-truths or flat-out lying about the truth. Both being overly positive and being overly negative do this. However, from personal experience, most places which affect one's personal life and cannot be reasonably skipped (unless you wish to live close to a poverty wage, and even that is questionable) emphasize being more positive than need be. Negativity can more or less be skipped by just unplugging social media.
Take the classic "why did you leave your previous job" question in job interviews. Most people leave jobs over something which cannot be interpreted as anything else but negative. Bad bosses, bad managers, no growth, no opportunities, too little pay to support future goals. Yet negativity is a no-no (as is "greed" and a bunch of other things). So yes, most people are decorating or lying about the actual reason. And no, this question doesn't exactly indicate any kind of job performance, it's more like a hazing ritual. Same goes for other questions.
It's a weird kind of dystopia for people who are primarily logic driven and/or horrible at selling themselves, and don't have a skillset so in demand they can ignore those barriers. Let alone those who are vulnerable to this kind of behavior (people who are too modest for their own good and anxious to boot come to mind).