alt Hacker NewsI think both parties probably benefit; people who are more likely to take the offer are those who have another reason to leave (unfulfilled, etc). This will benefit the company in the long run because they can eventually replace them with someone who want to join (people applying for the job).
Can go the other way though: people who've been there for a while, are motivated and back themselves to get another job will take redundancy (i.e. the people you want to keep).
People who aren't motivated and/or don't back themselves to get another job will stay (i.e. probably the people you want to get rid of)