The Federal Reserve does play a relevant role, and it may well have tried to keep growth within a narrow band over the last two decades. If so, then the financial crisis might have started to show that the official GDP numbers of the last decade were a house of cards based on overvaluation of some sectors of the economy, and that we've actually been growing at a lower rate for quite some time.

I don't have evidence of this, but it is a hypothesis that confuses me less than the hypotheses of coincidence or a natural propensity to a 3.5% growth rate.