Sorry, this doesn't work for the many people who simply aren't equipped to WFH and are learning to work remotely. They lack the dedicated workspace at home, they have children/family/roommates who don't respect the "im at work" mentality, or they simply need a mid-afternoon nap, and as a result they have frequent and often lengthy periods of not working.

Would be fair to the employer if those people still adhere to a strict 9-5 schedule despite the lowered productivity? I think most reasonable people simply adapt and that's why we have articles like this pointing out longer and different work hours. It's not unreasonable at all.