In contrast, defined-benefit plans are sometimes criticized because their benefit structure and vesting periods, designed to encourage employee retention, can penalize mobile workers. However, mobile workers are still often better off in retirement with traditional pensions than with 401(k)s, especially since nearly half of 401(k) accounts are cashed out when workers change jobs. Are employer contributions steady and predictable? Employers need to be able to plan for the future and workers need to know that the benefits they were promised will be there when they retire.