[neilv]

I'd guess the CEO is creating opportunity for employees to say things to the CEO that they wouldn't be willing to say to some others.

(Maybe employees have feedback on mid-managers, their team, or something else the company is doing, and don't feel they can raise it lower on the org chart, or haven't been successful at that.)

If it turns out employees do have something to say, and not comfortable with everyone hearing it, then they have to ask themselves how much they trust the CEO to honor the confidentiality commitment, and not throw the messenger under the bus.

I'd guess intent of not-anonymous might be that be CEO wants people willing to stand behind what they say, which would be a desirable property of an organization. Or maybe it makes the information more actionable.

Also be aware that company staff might be able to determine what individuals say, due to "endpoint security" mechanisms, other IT implementation, trivial traffic analysis, etc.