If a saver attempts to live off the interest on his nest egg, the results are catastrophic over time. He better hope not to live very long. So if you just want to keep up with inflation, you can accomplish that limited objective with debt instruments, but not much more. Most of us want an inflation hedge, growth and the ability to make withdrawals. Debt instruments haven't been able to support that.
Savings are a unique and treacherous form of capital punishment.
Every day, millions of well-meaning savers unnecessarily punish their capital and prevent it from growing and thriving. Many advisors set the real rate of return as a long-term target. Prudence and realism would dictate use of the more conservative data for planning. If we get more, we will all be pleasantly surprised. No matter how you look at the data, equity returns swamp anything available in debt.