There’s a social code among coworkers. Nobody wants to be the person who rats out every mistake a coworker makes to a higher-up. Sometimes, small mistakes can be corrected at the lower level, and no CEO, CFO, or Editor in Chief cares to know about it. We learn this lesson very early on in life. Nobody likes the kid in school who is constantly telling the teacher about minor infractions, and no teacher likes that kid either. There’s a time and a place for everything. 

That said, there certainly is a time and place for talking about your coworkers to the CEO. If you’re meeting with them and talking about something noteworthy relating to them, mentioning something they’ve done, for better or worse, is not taboo. No employee works in a vacuum, and you can’t have productive conversations about work unless you paint the complete picture of what’s going on.