Comment by runarberg

One can argue that the instrument DJs master are the discs and the mixer. DJs have to know a lot of songs, know which keys they are in, know which tempo it is in, know the range of tempos two songs sound good together, know which keys sound good together when switching songs, etc. etc. Good DJs are indeed experts. If they wanted automation they would just pick a Now record or a Spotify playlist and play it through.