Because Apple support is not there to answer questions about products you intend to buy. It's there to give support about products you already own. If you have issues with them, etc...
If you need information about a product you want to buy, you can contact Apple Sales instead of support.
From: http://apple.com/contact
Apple.com is a convenient place to purchase Apple products and accessories from Apple and other manufacturers. You can buy online, chat, or call (800) MY–APPLE (800–692–7753), 7 days a week from 7:00 a.m. to 11:00 p.m. Central time.