This might be true if you have everything in cash in a safe at your house and plan on taking out fixed amounts for the rest of your life, I guess, but who are those people?
Most people are on social security, which is inflation adjusted.
Others with more wealth have retirement savings, which are likely mostly in bonds and stocks, which weather inflation not too shabbily. Interest rates go up, and banks start actually yielding interest!
Prop 13 passed mostly as a populist revolt against taxes, but in reality it does a lot more for people in their prime of earning and a toooon more for commercial property tax cuts than it does for retirees.
Every other state has better tax deferral mechanisms, and given the tiny fraction of Prop 14 effect that goes to retirees, I don't really buy this back formation of what was going on. If people really voted for such a lie, it wouldn't be the first time with propositions but from the media I've seen from the time I really don't think people were that duped and probably knew the broad effects of Prop 13.