You'd get players who wouldn't want to share to controller.
But 100 people at a community day seems kinda insane. I imagine that getting feedback from 8 people made the devs heads spin, especially if they were getting called over to the builds and getting "Fix this...This needs to be like this.." etc...imagine that x 12. They'd have to have an email system set up just for that day to organize all the feedback, so that the devs' heads wouldn't explode.