You make it sound like employees are perfect and communicate transparently at all times. Many people lack the ability to be self critical and want to avoid confrontation. That often leads to surprises, a managers worst friend.
Modern workplaces forced quarterly reviews, thus there should be no surprises. In practise reviews actively prohibit employees from communicating transparently.
This is, if you've been burned by a company getting rid of you after being transparent, you are never going to be transparent again even if it would be in your favor. Then when you look at most companies thinking the most important thing is how much profit they are going to make next quarter that quarterly meeting stops looking like an event to see how you are doing, into one where the company determines how much blood they can extract from your withered corpse.