Not sure what you mean by this. Most retirement accounts are investment portfolios. I don't think they meant that people should reinvest their entire portfolio in the offering, or invest money they couldn't afford to lose.
The typical guidance is to shift towards bonds and short-term instruments in a fund or ETF over time. The problem with that is that the yields have been poor for many years.
A nominally safe investment like the Vanguard Short Term Gov Bond ETF is down in real and nominal terms over the last decade.
edit 1.75%
extra tennis balls for your walker