Really, its all about trust. People need to trust that what they say won't be twisted around and used against them.

The challenge is that the percentage of people from the population of people who want management responsibility that are willing to manipulate the situation for their own gain, is higher than the control population. Which means that people get exposed to them as managers more often than is ideal (in the ideal case they are managed to understand that 'winning' is a high level of trust on their team, but that doesn't happen often enough)

Just one of the ways that sociopaths have made life less enjoyable.