Remember, corporate pensions were a big thing when the US was at it's greatest economic strength (post-WW2) and the internet with all of its modern tools to make investing much simpler for the average person didn't exist. You had to pay brokers for every single trade or someone else to advise you or you had to just buy and hold a small set of stocks for 30 years and hope those companies would still be around (a fair bet at that time).
Back then companies didn't really go under like this. If anything, they got bought by a larger company and merged, but the frequency of that was nothing like today.
Today, with health care costs what they are, having pensions and defined benefit plans are insane to me. It's much better for the company to say "we will match x% in a 401k". They are defining their contribution and it has a cap. If anything happens to the company, the employee's funds are safe as the money is already transferred. For the employee, it does require them to manage this money but that's far easier and cheaper today and that money doesn't require the company to be around forever. If things tank, the employee is protected.