I suppose pensions take advantage of the time value of money; funding someone's 401k means you can't use the money to expand your business, but if you just pay them what they would have made 30 years later, you already expanded and that money is easy to come by because you're making so much now. But, it's difficult to enforce. The expansion plans could be "yacht for the CEO plans", and when retirement time comes, "oh sorry we don't have any money :(" is the likely excuse. So it doesn't seem to work anymore in practice; being optimistic about doing better than average long-term is not a viable financial strategy.
