In the 2016 paper “Does Working From Home Work?” a team of economists looked at Ctrip, a 16,000-employee Chinese travel agency that had randomly assigned a small group of its call-center staff to work from home. At first, the experiment seemed like a win-win for workers and owners. Employees worked more, quit less, and said they were happier with their job. Meanwhile, the company saved more than $1,000 per employee on reduced office space. But when Ctrip rolled out this policy to the entire company, it caused a mess. One complaint swamped everything else: Loneliness.