The two outs mean you can plug into the receiver's battery jack plus either "Y"into another jack or into an unused one. Is it a single failure point? Yes. But it's designed to fail open so one (or both)battery(s) will still power the receiver. The receiver being a whole box full of "single failure points."

If your batteries are matched you pull the same voltage whether it's one or two in line at the time (parallel).

If a dual battery system fails in a closed circuit the dead battery will be like adding a big resistor to the good battery and drain it quickly. Granted, a battery failing in a closed fashion is rare, but so is switch failure . . . which is the reason to use two switches.