You have to pay them to leave. You have to endure the publicity of large scale layoffs. This way, you are progressive, agile, and team oriented.

Because the cost of firing (dismissing) someone depends on where they have their contract. It might be zero cost in the US but the US is not the World. In Europe it would cost them tons of money to remove hundreds of jobs in a single swipe. OTOH, let people leave, no cost for them.

In a large bureaucratic corporation, individuals are never "fired". They are "managed out".

Check out the book Corporate Confidential.

They don't know who those people are :)