But I wouldn't be surprised if at the end of the exercise, they actually really do end up unearthing some weaknesses that the process feedback mechanism failed to put sufficient spotlight on.
I mean, how else do you actually test the process feedback mechanisms? I realize that nobody does that, but you'll never know if that mechanism truly works unless you let your CxO do all the work end to end and then ask them if they had sufficient awareness about each small point of friction they encountered.
Another more subtle detail: not sure if DoorDash experiences this, but in my experience it can be difficult to get a newly poached manager from a different company to wrap their head around how - and why - this company is different. The more experienced people are, the more they tend to reach for their old playbooks, which can be good and bad.
You do have a point that large parts of the company could have been carved out (eg: the communications team), and the exercise would have still yielded the same insights, which is why in the end this is a publicity stunt.