The uncouplers were designed way back when, and it was assumed that they, being toys, needed to be easy to install by the average kid and his dad, and fool-proof.
Of course, we all are subject to "if it works, take it apart and find out why" syndrome and its corollaries. But making the controller to the uncoupling/unloading track constantly powered introduces some unintended consequences. The powered-by-the-track feature means that it can't be left powered when not needed. A stray unintended button activation (never discount the abilities of a cat or guest) or a crossed wire can start an overheating situation.
It's best to leave it the way it was made at the factory and do what the man said: Put the train in neutral and adjust the track power to the minimum needed voltage for reliable operation.
