The rules that govern what gets approved and what doesn’t in Apple’s App Store have always been a little mysterious. But a new Bloomberg interview with Phillip Shoemaker, a former Apple exec who oversaw the App Store’s approval process between 2009 and 2016, offers some interesting insight. It’s particularly relevant at a time when Apple faces antitrust challenges in both the US and the EU over its management of the App Store.

In the interview, Shoemaker says that Apple has long feared that rival apps from companies like Google and Facebook would replace core iOS features like calling and messaging. He notes that this fear is “absolutely the reason” that the company still doesn’t let users set third-party apps as the default service for these primary functions.

“That was a real thing. I mean the fear that somebody would come along, a Facebook, a Google, whomever and wipe off and remove all of our items,” says Shoemaker.

Talking through the early days of the App Store, Shoemaker notes that the approval process used to be pretty hit-and-miss. He recounts an incident in which a notorious “baby shaking app” was approved, driving down the company’s stock price. Shoemaker says that this mistake earned him a phone call from Apple founder Steve Jobs himself.

“Steve just had simple words for me: ‘You’re stupid and you hire stupid people.’”

“Steve just had simple words for me: ‘You’re stupid and you hire stupid people,’” he says. “This was one of the best conversations I had with Steve. It was so succinct and to the point. He hung up the phone.”

Looking to more modern times, Shoemaker notes that there is inherent conflict as Apple enters markets “ripe with competition.” This certainly fits with Spotify’s complaint against the company, which says the iPhone-maker has abused its control over the App Store to penalize rival music streaming services.

“I’m really worried about the competition piece,” says Shoemaker, about 20 minutes into the interview. “You see Spotify going to the EU regulators [and] you have Elizabeth Warren talking about breaking Facebook, and Apple, etc ... I believe that there is now a conflict as Apple goes into these spaces that are ripe with competition.”

Shoemaker goes into more detail about the specific rules he thinks Apple needs to change in a blog post on Medium, noting that companies like Netflix and Spotify are “rightfully worried about fair treatment.” It makes for interesting reading, along with further quotes and the full interview with Bloomberg’s Mark Gurman, available right here.