Source: How Computers Work by Ron White
The deskless PC has long been computing's holy grail, a computer that slips the bounds of keyboard and cables, of monitor and mouse, to soar free as a bird-a bird endowed with a constant feed from the Internet, applications that will run a multinational corporation, and on easy abandon that lets it go with you anywhere, like a parrot perched on a pirate in pinstripe.
Why do you think there are no indefinite articles in front of keyboard, monitor and mouse? After all, you're never going to say something like this: "I'm going to the store and I'm gonna buy bottle of milk, fork and can of ground meat." Sounds very ungrammatical, doesn't it?