I thought it was pretty well understood that the purpose of these companies is to overhire overqualified people simply to keep them busy doing things that are just enjoyable enough, with great perks, that they won't consider leaving the megacorp and focusing their talents to create viable startups that are a genuine threat to the monopoly.
It's not a myth. Executives just don't do as much as you think and the numbers don't need to make economic sense when you have a bottomless VC fund to pull from.