It seems an obvious answer would be that there has been a lot of growth outside of the 500 large companies picked to comprise the s&p 500.
The s&p 500 is not an index of all corporate growth.
The s&p 500 is not an index of all corporate growth.
The S&P 500 and DJIA are limited to a fixed number of corporations. The NASDAQ is allowed to expand it's number of listed companies over time.
If you look at the NASDAQ figures it's able to show considerable and relevant growth, as more companies have listed. (Still not at 2000's peak, but much closer than the S&P or DJIA.)