A person's perception is highly informed by how well or poorly they understand the subject or situation in question.

Let's say you got stood up by a first date because they got hit by a car on their way to you. Your perception of them is going to vary wildly depending on whether or not you know the facts behind why they didn't show up.

Similarly, knowing how you actually fit into things at your job - i.e. your importance to your working group, the company, it's customers, society itself, allows you to have a more accurate set of facts to base your perception on.

So yes, the truth matters.