Major Tom
Thinks s/he gets paid by the post
According to a calculator, the annualized S&P 500 return from January 2000 to September 2017 is only 1.076%. It would be 2.977% with dividends reinvested. So valuation does matter. When you retire does matter. Money should be discounted when the valuation is high.
2.97% real return doesn't sound too bad to me. I am financially simple, so excuse me if I'm missing the point, but the problem I have with these reports of supposedly low returns between selected dates is that very few of us put all of our money into the market on one date and then withdraw it all on one (different) date. Rather, we DCA into the market over many years, and do the same in reverse when retired, hopefully also over many years.