Harry and Furious raise valid points. I know, folks don't like their position.  But, do we think businesses exist to pay people?  No!  They exist to fill a market, and make money for their owners (I know, "greedy owners!!!").  If the business owner is able to increase revenue for the business, and in so doing is able to pay employees more, then it makes sense to hire the most-productive workers.

Now, you can argue all you want about who is more productive.  I don't have those stats, if they are available.  But, as Furious says, if the new employees are more productive, then the fired employees were not as productive as the position warrants.

Few businesses exist simply to pay employees.  The reality is, businesses must hire the most-productive employees so they can stay in business.  If a business goes out of business due to no profit, all employees are out of work.  Where is the benefit of keeping the less-productive employees around, then?