Oh, that depends very much. Some other reasons include limit resale/kill secondary market/otherwise control distribution, track users/usage, be able to force update/patches/deactivations/etc on users, your publisher is an idiot.
Oh, that depends very much. Some other reasons include limit resale/kill secondary market/otherwise control distribution, track users/usage, be able to force update/patches/deactivations/etc on users, your publisher is an idiot.