Who is this they?
[1] https://www.sciencedaily.com/releases/2013/03/130325183819.h...
[2] Desai SV, Feldman L, Brown L, et al. Effect of the 2011 vs 2003 Duty Hour Regulation–Compliant Models on Sleep Duration, Trainee Education, and Continuity of Patient Care Among Internal Medicine House Staff: A Randomized Trial. JAMA Internal Medicine, 2013; DOI: 10.1001/jamainternmed.2013.2973
Key finding: "In summary, the literature still does not definitively tell us whether limiting duty hours improves patient safety."
As an analogy, imagine reducing your cheeseburger intake from 60 per week to 40 per week: it probably won't have a huge impact on physical fitness.
The hand-off issue is also weird because it's at least theoretically improvable, whereas there's no real way (barring go-pills) to reduce sleep-related issues.
[0] http://www.nejm.org/doi/full/10.1056/NEJMoa1515724#t=abstrac...
Neither one of these schedules is really "reduced" compared to any sort of typical level: they're both ~80 hrs/week (and probably more).
From the paper:
"Programs assigned to the flexible-policy (intervention) group were required to adhere to ACGME duty-hour requirements of limiting work to 80 hours per week, 1 day off in 7 days, and on-call duty no more frequently than every third night, but they were granted a waiver by the ACGME to waive four duty-hour requirements (from the 2003 and 2011 reforms) concerning maximum shift length and minimum time off between shifts (to facilitate continuity of care) (Table 1)"