I think one could reasonably attribute the growth for the first decade or two after tax rates began increasing to the momentum built up during the previously laissez faire era.
Supply chains, investor sentiment, etc all take time to change so a tax hike might not make its effect on GDP immediately evident.
Also, many investments have a time delayed effect on GDP, like large capital projects which can take a decade to complete. Investments in the lower tax era could have only begun outputting goods well into the new high tax era, giving the false impression that the high tax era was responsible. Think a factory that takes a decade to come online for example.