So, where is the research paper or something. We can't just trust 'leading sleep scientist'.
I am kind of skeptical of the ever-increasing amount of recommended sleep. Apparently pre-industrial humans only slept an average of 6.5 hours a night. Sure, many pre-industrial humans also arguably live in worse material conditions than some of us today. But sleep science studies still do not seem very rigorous or convincing (many are based on absolutely tiny populations) and it all seems rather consistent with a cultural reaction against workaholism.
I think there's a confusion between "sleep", where you're in bed but still awake, and sleep as in actually being asleep. This is specifically called out in the article where it says "if you’re in bed for eight hours, a healthy sleeper might actually sleep for only about 7.2 hours."
You're forgetting napping! A mid-afternoon nap makes up for the shortfall, but 'workaholism' effectively ended that practice.
My wife is very self-righteous about her lack of "need to sleep" - she stays up all night, sleeps four or five hours, and goes on and on about how she's just "wired differently" than the rest of us and doesn't need as much sleep as us "lesser mortals". Then as soon as I turn on the car or start a movie, she's out like a light.