In practice it is. People use it as a synonym for trickle down economics. As in, the billionaire's yacht rising with the tide will somehow trickle down to the rest of us.

I personally first encountered it when a Republican Member of Congress worth nine figures said it, the intent being to argue in favor of trickle-down and against taxing the rich. "What helps us ultimately helps you!" You're right that it's surely not the original intent, as it was popularized by Kennedy. I could've framed it all better. I was responding to it as I'd personally heard it used.