> Facebook said it used to have a step in the account verification process where some users had the option to confirm their email address and voluntarily import their email contacts onto the site. The feature was meant to help them find their friends more effectively and improve ads, according to the company.

> That process was redesigned in May 2016. While the language, which explained the step, was removed, the feature itself was not, Facebook said. Hence, email contacts were still being uploaded to the site without users being aware of that fact.

The claim isn’t that the feature was created by accident. It’s that they failed to disable the feature in the backend when they removed parts of the UI. I can definitely see how this could happen by accident due to poor communication between managers and engineers across different teams. You could also choose to believe that it was an intentional error.