I've seen folks do this with and without inflation adjustment as a poor measure of their savings & investing efficiency. Those comparisons fell apart as the older crowd had more years for money to compound. Perhaps it could be done with the SP 500 as the index as that might give a more consistent comparison in investing efficiency through time, though it would mostly tell us that if we just had worn rags, lived under a bridge and avoided eating for the last several decades, we'd be awesomely rich. But I can't understand what using the AWI as the index tells us.
It makes some sense for the SS administration to index benefits with average wages. Otherwise there would be a huge disparity, where the oldest retirees would get way less than younger retirees and early jobs would mean hardly anything to your benefit (since they switch from AWI to CPI-W eventually, this still happens, but not so much as to cost politicians their jobs). But AWI means nothing individually in terms of how well we saved or invested, it's not like we could invest in it.
It makes some sense for the SS administration to index benefits with average wages. Otherwise there would be a huge disparity, where the oldest retirees would get way less than younger retirees and early jobs would mean hardly anything to your benefit (since they switch from AWI to CPI-W eventually, this still happens, but not so much as to cost politicians their jobs). But AWI means nothing individually in terms of how well we saved or invested, it's not like we could invest in it.