The real problems are that the average worker doesn’t have a clue how to actually invest money- they mismanage it both in the actual working/saving phase by either not investing enough early enough, or they screw it up when they’re supposed to actually live on it by getting those cartoon dollar-sign eyes and spending it too fast.
There needs to be some kind of common ground- like maybe not defined benefit, but more like you are required to contribute some amount, and the company is required to match some percentage, and then it’s all centrally managed and voted on by a stakeholder group, etc… And pays out at some defined rate after retirement.
That way, employees and retirees would see a lot of the benefits of defined benefit plans (but not all), and companies would be insulated from some of the drawbacks.