For me a lot of the events I do the crowd is looking for me to mix. That's what some who have been to an event I've done before expect and would be pissed off if I didn't.
I could mix without a controller using the left and right arrow "nudge" keyboard shortcuts to keep beats matched up, but the jogwheels on the DAC-3 controller were much easier and what I had been used to with my dual CD players. It's not like I wasn't mixing at all.