HR can create a policy like this to prevent managers from locally optimizing. Firing someone is a lot of work for a manager. It is easier for the manager to transfer that person, than to deal with the problem themselves (even if they really should be fired).

HR might also create a policy like this to improve the average quality of employees. An employee who underperforms on team #1, is more likely to underperform on team X than a randomly chosen new hire.