One reason, I imagine, Facebook made this choice as a company is to increase the amount of real estate their apps have on the app store and 'top 10 most popular apps' lists, similar to how companies strive for top listings and more real estate on search engine results pages.
Between Facebook, Instagram, and Messenger, I wouldn't be surprised if Facebook's apps occupy 30% of most top-10 lists.
Between Facebook, Instagram, and Messenger, I wouldn't be surprised if Facebook's apps occupy 30% of most top-10 lists.