I wouldn't call it a psychological barrier so much as a game-theoretical one. If an employer knows that an employee is looking for jobs, their continued employ

I wouldn't call it a psychological barrier so much as a game-theoretical one. If an employer knows that an employee is looking for jobs, their continued employment would be at risk, they could be silently passed over for promotion, etc. I suspect that most people posting in WWTBH are currently unemployed.