Hypothesis: taxation determines rate of return…but not in the sense you may think.

Maybe , just maybe, they want interest rate on bonds to be high because interest is taxed at a higher grate than long term capital gains…capital gains are taxed at 20-28% for the money that matters (lower AGIs pay 10-20% for cap gains), but interest and dividends are taxed at 37% for high income earners (0-37% for lower income earners).

Maybe they want to have high interest rates to boost taxation…until unrealized capital gains taxes become a thing, this is the only way to steal money other than inflation: propping up yield.