I'm old enough to remember those times, and it was always bullshit. Economists called trickle-down "voodoo economics".
"Conservatives" never have a single fact on their side, anywhere or anywhen as far as I can tell. All their apologists are always making up bullshit to justify maintaining a perpetually expanding pyramid rather than a just society. Marx mansplained it over a hundred fifty years ago and the abject failure of a pyramidal, feudal society was made undeniable by WWI.
We've been inhabiting a post-factual fantasy since then. This is a good place for one of my favorite quotes:
"The point is that we are all capable of believing things which we know to be untrue, and then, when we are finally proved wrong, impudently twisting the facts so as to show that we were right. Intellectually, it is possible to carry on this process for an indefinite time: the only check on it is that sooner or later a false belief bumps up against solid reality, usually on a battlefield."--Orwell, 1946
Thanks for giving me a soapbox :)