I've seen it happen several times over the years. This particular time, he was using a Spektrum but I know I've seen it happen even with older stuff.

Another application/need is that when we line up, it would be nice to "turn off" the truck so it's not wasting juice waiting for the stragglers to get to the line but the BEC switch won't help that, fans will still be running and such... I think about my 1/10th stadium and how nice that on/off is...miss it.