In a lengthy - but really really good - Bloomberg profile on Instagram and the issues it’s having being a Facebook product, here’s a fun tidbit:

In 2015, Snapchat—the photo-sharing app that Facebook had tried to buy years earlier—started stealing Instagram’s core audience of American teens. Snapchat’s killer feature was known as “Stories," ephemeral video updates that disappeared 24 hours after they’d been posted. People could also put cartoon face masks on selfies and draw annotations, which made the app seem like a fun alternative to Instagram’s polished artsiness.

Krieger and Systrom refused to build look-alike functionality until Zuckerberg personally requested it, according to a person familiar with discussions. Zuckerberg worried that if Instagram didn’t do something to change its product, such as copy Snapchat, it risked missing out on an entire generation of users.

And now you know how that happened.