For company plans, you said the answer. It's silly to assume that your employer will be alive when you are 80 year sold, and also seems like a stupid idea for a

For company plans, you said the answer. It's silly to assume that your employer will be alive when you are 80 year sold, and also seems like a stupid idea for a company in a completely unrelated business to get into the retirement fund mgmt business. For states, the reason is population. If your pop doubles every 50 years, then you only need 2 young people to pay for one retiree. If it's the opposite (Japan now, US in a few decades), then you are screwed.