The people who are closest to a thing are often the most wary of it. Technologists know how phones really work, and many have decided they don’t want their own children anywhere near them. For instance, Athena Chavarria, who worked as an executive assistant at Facebook and is now at Mark Zuckerberg’s philanthropic arm, the Chan Zuckerberg Initiative, said: “I am convinced the devil lives in our phones and is wreaking havoc on our children.” Ms. Chavarria did not let her children have cellphones until high school, and even now bans phone use in the car and severely limits it at home.

She said she lives by the mantra that the last child in the class to get a phone wins. Her daughter did not get a phone until she started ninth grade.

“Other parents are like, ‘Aren’t you worried you don’t know where your kids are when you can’t find them?’” Ms. Chavarria said. “And I’m like, ‘No, I do not need to know where my kids are every second of the day.’”