I see where you are coming from, but masterful DJing takes much more than switching from desk A to desk B. Song selection is crucial, it's even more important than transitions, moreover you need to play the right music to the right audience. Those things you won't find in tutorials, and that's what makes a great DJ set great. On top of that you can combine producing with playing live by adding effects, creatively transitioning between songs and cue jumping, this takes a lot of skill too.