A few years back, Brandon Gell, chief operating officer of Every, an artificial intelligence–focused media startup, couldn’t stop staring at a photo taken at the headquarters of another startup, Notion, a maker of productivity software.

“It was of their entryway, and it was just shoes—this mountain of shoes,” he recalled. The pile of footwear was an inevitable daily outcome of Notion’s no-shoes policy for employees. “I was like, ‘Holy shit, you can be a serious person—in a serious business—but still be comfortable.’”