For Krieger and Systrom's part, the co-founders vaguely addressed the controversy with a somewhat weak vote of confidence in their blog post.
Mosseri joined the Facebook behemoth in 2008 as a designer, and worked his way up into the role of Facebook head of news, where he had to deal with the fallout of accusations that Facebook did not do enough about fighting fake news and other misinformation that fills up the social network.
"We are thrilled to hand over the reins to a product leader with a strong design background and a focus on craft and simplicity", Systrom and Krieger said in a press release.The pair announced their resignation last week without giving a clear explanation.
Systrom and Krieger were still heavily involved in day-to-day product decisions at Instagram until their departure.
Mosseri has been at Facebook for more than 10 years, where he's held a variety of positions including design director for Facebook's mobile apps and lead for the News Feed, where he tackled such hard issues as the spread of misinformation on the social network. "We're confident that under Adam's leadership, Instagram will evolve and improve and we look forward to the future of the product and community". In a blog post, Systrom said he and Krieger were taking some time off to "explore our curiosity and creativity again".
Facebook made its first billion-dollar purchase in acquiring Instagram for $1 billion in 2012. He was recruited to the Instagram team recently.
Facebook executives reportedly expected Instagram to more willingly integrate with the main product as a display of gratitude for the growth and resources Facebook gave it that allowed it to grow past 1 billion users and stave off stiff competition from Snapchat. "We believe that Adam will hold true to these values and that Instagram will continue to thrive", they added.
She also sought to downplay the impact of last week's data breach, in which hackers gained complete access to 50 million Facebook accounts by stealing their login tokens.
Facebook representatives have not commented on reports that the Instagram founders left the company amid tension with Zuckerberg over the app's direction.
Instead of complying with Apple native app rules, Facebook's Instagram is ditching its Apple Watch app in favor of notifications.