Unless you're doing a live set or some more creative things on 3 decks/ other hardware, the laptop in the booth is amateurish. especially if you're maxing a 2 tracks simultaneously. Even in genres like Jersery Club, future beats, etc where controllers laptop are popular, experienced selectors and artists move on from that setup.
... why? Who cares what the source of the music is? As long as the DJ picks good tracks and has a good mix, why on Earth would it matter what equipment they're using?
Culture. Hip-Hop, House/Techno, Reggae/Dancehall cultures place emphasis on the skill in manipulating the music via a turntable (and CDJs like the club standard Nexus.) Because of that, there is an association of quality with being able to perform well on turntables/CDJ and a mixer. Also, in genres like House/Techno/Reggae/Dancehall, there's a lot of quality music that only exists in a vinyl format for this reason.