Apple has certainly done this before:
Apple Literally Stole My Thunder https://medium.com/wwdc-round-up/253aed27a455
Apple rips off student's rejected iPhone app - iOS 5 lifts idea, name, even logo http://www.theregister.co.uk/2011/06/08/apple_copies_rejecte...
Konfabulator, Dashboard controversy flows out of WWDC http://www.macworld.com/article/1035200/konfabulator.html
Apple stole Karelia Watson http://forums.macworld.com/index.php?/topic/2477-apples-stol...