If you always used one computer that would be fine. But if you create your account on your home computer and then want to use it on your work computer, your ipa

If you always used one computer that would be fine. But if you create your account on your home computer and then want to use it on your work computer, your ipad, your android phone, and occasionally at your brother's house then we need some way of authenticating you instead of your computer. And even if you don't want to log on from any of those places, eventually you are going to get a new computer.