Late but here goes.
This is like when Trump said that foreign countries pay tariffs. Like Byron Donalds in the article you linked, he’s just wrong.
Foreign countries don’t pay tariffs. Domestic producers have always paid the statutory toll, and most of the time the economic incidence too. No textbook has argued argued otherwise, because this is just the standard.
It’s not that Trump is advocating a different policy when he says foreign countries pay tariffs, it’s just that he (like a lot of other MAGA Republicans) so grossly misunderstand economics and their own party positions, that they end up advocating for a different thing. In this case, Byron Donalds is even going as far to advocate the pejorative version of his own side.
Now if you’re saying that trickle-down has become so widespread that even supply-side supporters have become fooled into thinking that it’s their side, I’d happily grant you that. But what I mean when I say that trickle-down has never been “seriously” advocated is that it’s never been in textbooks. There are no policy appropriations made by legislators to support the goals of trickle-down economics.
Similar to how Republicans nowadays accuse Democrats of trying to bring in illegal immigrants to bolster their voter base (a pervasive lie), to try and “debunk” such a policy would be intellectually dishonest, since the Democrats have never advocated such a thing.