Because the motivation of a lot of the people arguing for "raising taxes on the rich" is to indeed leave the curve altogether.
Will small increases or decreases in tax rates fundamentally alter GDP? I think obviously not.
But those attempting to make a data-based argument for introducing MMT or a UBI with significantly nationalized elements of the economy (healthcare, energy, etc.) are laughable, when the evidence is so overwhelming that these ideas lead to adverse outcomes in the long-term.
I'm not attempting to straw-man, just to cut the meat to what people are actually arguing about (which isn't a couple percentage points in a tax rate). And it's important to flip it and be honest...and say, no, the data does indeed show without question that freer societies are way better -- and it's just that simple.
This is just absurd. "Better" is not a metric.
By the metrics most widely used worldwide, the Scandavian countries are "better" than the US, while also being "less free".
You may disagree with the metrics for "better", and/or you might disagree with the metrics for "less free", but the core point is that these things are not simple.
This is just a laffer-curve-style argument. Draw a graph. Point to one end, and mumble. Point to the other end and mumble something else. Say "We want to be here" while pointing somewhere on the curve.
While it remains unhappily true that lots of people are taken in by this sort of argument, it also remains true that it's an astonishingly weak sort of argument.