It's always funny to me when people assume that sleep works the same for everyone or that it is as simple as scheduling something on a calendar. Neither are true.
As an anecdote in the opposite way, I am a sort-of night owl (my peak hours are roughly 10:00pm to 1:30am). As a teenager I was a late night, late morning (4am to 2pm) sleeper. Around 17, I started training at 7am, meaning I had to be up at 5:45 every morning. When I eventually quit after about 4 years, it took me another 4 years to un-learn the habit and move back to being an evening person.
And I certainly adjusted from my "classes start at 7am" in highschool schedule to my "classes start at 12pm" schedule in college near instantaneously.
It helps that I'm not very good at sleeping on airplanes unless I've been awake for >30 hours
I get pretty wiped out for a week when the clocks go forward or back. I'm only marginally productive when the sun is up, but get a huge amount done from about 8pm to 2am.
But so what? That's me. I don't expect the rest of the world to be the same.
Sleep is clearly very individual. Standard school/office hours are a hugely inefficient waste of the potential of tens of millions of people.
It should be possible to design a more flexible system. But we still have ridiculous notions that early risers are somehow the model of virtue, and everyone else should aspire to the same hours.
The paper itself seems to consider the effect to be largely genetic in origin, which I assume is probably a well-supported conclusion from other studies.