I honestly had never even thought about where in the org it stops... But seriously, no CEO team would cut 10% of their executive committee each year. It would be a sign that they don't know how to properly vet candidates, and be terrible for morale and turnover...

VP level often has fairly high turnover, maybe that's where this originates from.

In my experience at the VP level you have many highly skilled reports who are gunning for your job. Once you get the VP job then there may be many more enticing opportunities at other companies with just tough competition in the current position.

Why stop at C suite? Stack rank the board of directors too for good measure, and do it by shareholder vote of confidence.