Voltage regulators are required for any servo driven bot. Take the one I just built for Shane for example: It uses 3 Park Flyer servos, which can (for short lengths of time) operate on 7.4v (a 2 cell lipo). The receiver (a Hitec feather) cannot. Ive rigged it so that the 3 servos get 7.4v power by putting the positive wire before the VR chip. the VR outut then goes to the RX, powering it with 6v (which it can handle). The negative (Black) and signal (White) wire from each servo goes to the RX, not carrying any voltage, and getting signal from the RX.

since most ants these days use motors and speedos, the speedo serves to power the RX via a BEC, usually 5v, so VRs have not been used much. They are still used in the remaining servo driven bots, Like shanes new one

PS: 600 posts !