Apple's curation has almost entirely been focused on eliminating duplication (even if better) of Apple-provided solutions. Do you have any sources to back that

Apple's curation has almost entirely been focused on eliminating duplication (even if better) of Apple-provided solutions. Do you have any sources to back that assertion up? In the WWDC keynote, Jobs indicated that the three major reasons for rejecting apps were bugs, use of private APIs, and apps not delivering what they promised, which would be a direct contradiction of your claim.