Exactly. setting up multiple 5%+ cds maturing at regular intervals over the next few years is basically safeguarding a future income stream than can periodically be drawn on or reinvested at a future time. Having cds might save a person from selling other assets to raise cash when the markets are not favorable. Or they may provide capital for a future opportunity that a person is not aware of yet. There are few safer places to squirrel away funds that don’t have a specific purpose right now.
This really gets into having a balanced portfolio that allows you to weather volatility, especially if you're retired/drawing down on your investments. CDs/cash-equivalents are good for exactly what you describe - not needing to sell volatile assets that are currently down.
Would be interesting to have a thread on this topic.