I think you're deifying Stewart and holding him at an inordinately high position. Rachel Maddow? Daily Show is about politics and news, but it's a comedy first and foremost. Given that many correspondents - John Oliver in the past - took over for Jon and that Jon has had a history of grooming his correspondents' comedy to be razor sharp - Colbert, Oliver, Carrell, Helms, Wilmore;etc. - I'm not particularly sure why you think it's odd people think a correspondent, hand picked by Jon himself, should take over following his departure. The Daily Show has a very good track record of taking capable comedians and giving them a great tool set to make great hard, biting political takes even outside The Daily Show.