Required? Not if all of your motive power and lighted cars go through the frog without stalling or flickering. Try it, and see what happens.
I do power all of my frogs, because, over time, wheels get dirty, and while they may run great now, at some point, they will stall or stutter.
Hope this helps,
DFF
By the way, I may have some extra 224S throws that you can have, if I can find them and you want them.